European Union president Donald Tusk said on Friday the bloc was determined to stay unified after Britain voted to leave and warned against "hysterical" reactions.
"Today on behalf of the 27 leaders, I can say that we are determined to keep our unity as 27," Tusk told reporters in Brussels, adding that "it is a historic moment but for sure not a moment for hysterical reactions."
Tusk said that the bloc would meet without Britain at summit next week to assess its future.
Czech Prime Minister Bohuslav Sobotka says the British people's decision to leave the EU "is not the end of the world and above all not the end of the European Union."
Sobotka says Britain has decided to take "a different road than European integration. This decision is serious and irreversible."
In a reaction on Facebook, the Czech leader said Friday the EU has to work to minimize the damage to EU and Czech citizens.
"The EU has to change. Not because Britain left, but because the European project needs much stronger support from citizens."
"The EU is for us, the Czech Republic, the best possible guarantee of stability, peace and prosperity."
Sobotka said Britain will become less important and will be struggling to keep Scotland in the U.K.
Greece's prime minister said the British referendum dealt a severe blow to European unification, and should force a shift toward more "democratic" practices within the European Union.
Alexis Tsipras who, a year ago, nearly presided over debt-crippled Greece's exit from the Eurozone, said Friday that the vote "confirms a deep political crisis, a crisis of identity and strategy for Europe."
He called for a swift change of course in EU thinking, saying politics must retake the lead "from the economy and technocrats. "The British referendum will either serve as a wake-up call for the sleepwalker heading toward the void, or it will be the beginning of a very dangerous and slippery course for our peoples," Tsipras added in an address televised live.
Hungary's prime minister says the issue of immigration and how the British "can keep their island" determined the vote on Britain leaving the European Union.
Prime Minister Viktor Orban, who says the ideal number of migrants entering Hungary is "zero," said Friday on state radio that the biggest lesson of the UK vote is that Brussels "must hear the voice of the people."
Orban said that Hungary is in the EU because "we believe in a strong Europe, but Europe is strong only if it can give solutions which make it stronger ... to significant problems like migration."
Orban earlier this week bought a full-page ad in British newspaper The Daily Mail, saying that "Hungary is proud to stand with you as a member of the European Union."
An estimated 300,000 Hungarians live in Britain.
Romania's president will meet with the prime minister and the governor of the central bank to discuss Britain's decision to leave the European Union.
Klaus Iohannis said Friday it would take Britain two years of exit negotiations and "we will negotiate so that Romania's interests are protected and we will look after Romanians who live and work in Britain."There are officially some 150,000 Romanians living in Britain, although the real number is estimated to be double that.
Romanian leaders have said they favor Britain staying in the EU. Romanian joined the bloc in 2007.
Sweden, Denmark, Norway
Scandinavian euroskeptic parties are rushing to suggest membership votes after British voters decided to leave the European Union.
In Sweden, which joined the European Union in 1995, the anti-immigrant Sweden Democrats wrote Friday on Twitter that "now we wait for (hashtag) swexit!"
The Swedish Left Party suggested Sweden renegotiate its deal with the bloc but leader Jonas Sjostedt cautioned he first wants "to know what Britain's new relationship with the EU looks like."
Kristian Thulesen Dahl, head of the Danish People's Party, said a referendum would be "a good democratic custom" while Pernille Skipper of the left-wing Unity List, called it "the only consequence of the British results."
Denmark has opted out of parts of EU treaties for fear of losing sovereignty.
Neither Sweden nor Denmark plans a referendum.
Danish Prime Minister Lars Loekke Rasmussen says "Denmark belongs to the European Union" and the Scandinavian country has "no plans to hold a referendum on this basic matter."
Loekke Rasmussen says being member of the 28-member bloc is "Denmark's best opportunity to influence the world."
He said Friday referendums across the EU "must be food for thought," adding it shows a euroskepticism "that we as decision-makers must take very seriously."
In Norway, which is not an EU member, Prime Minister Erna Solberg told Norwegian broadcaster NRK she was confident that the EU would "find solutions to this."
Sweden's Prime Minister Stefan Lofven said the bloc now faces "great challenges" when it comes to economy, migration, climate and security
Moldova's prime minister calls Britain's vote to leave the European Union "a sad day for Europe."
However, Prime Minister Pavel Filip said that Moldova would remain committed to joining the EU.
"This is a sad day for Europe and for Britain's European and international friends," said Filip early Friday. "The European project needs now, more than ever, to be reaffirmed and trusted."
"Moldova will remain attached to its EU road, despite the result in the UK, because we trust the European Union as a successful project"
Moldova, a country of 4 million located between Romania and Ukraine, signed an association agreement with the EU in 2014, angering Russia.
Poland's foreign minister says Britain's deciding to leave the European Union is "bad news" for Europe and for the many Poles — estimated at about 850,000 — who now live in Britain.
Witold Waszczykowski was speaking Friday before the official results of the British vote on EU membership were announced.
He says "I can only give a sigh: so it's done. This is bad news for Europe, bad news for Poland. ... The status of Poles living there will not change for now, but we don't really know how much Britain's status will be changed."
He said negotiations on Britain's new ties with the EU can take between two and 15 years but others have urged the Brexit talks be held quickly.
Dutch Prime Minister Mark Rutte is calling for a balanced disentanglement between the EU and Britain and said he did not see much interest in having a Dutch national referendum on EU membership as advocated by populist right-wing politician Geert Wilders.
Rutte said it was "important now, also in the interest of the Netherlands, is that we try to find a solution step-by-step and in a stable manner." He then headed off to Brussels to speak with top EU officials on the British referendum results.
Rutte dismissed Wilders' call for a Dutch vote on the EU, saying "I don't think the Dutch are currently interested in having a referendum on that."
The prime minister says the Dutch understand that "cooperation with other countries in a common market ... is vital for our country."
German Chancellor Angela Merkel called the result a "blow" to Europe.
The president of an influential German economic think tank said Britain's decision to leave the European Union is a "defeat of reason" and that leaders must keep the UK as integrated as possible in European markets.
Ifo Institute President Clemens Fuest said "politicians must now do everything possible to limit the economic damage."
He is pushing for quick action, saying that "it's important to bring about a conclusion of the negotiations as quickly as possible so that the phase of uncertainty over future economic relations is as short as possible."
Germany's vice chancellor says it's a bad day for Europe after British voters chose to leave the European Union.
Foreign Minister Frank-Walter Steinmeier said "The news from Britain is really sobering. It looks like a sad day for Europe and Britain."
Sigmar Gabriel, who is also Germany's economy minister, wrote on Twitter: "Damn! A bad day for Europe."
Finance Minister Wolfgang Schaeuble said that he had hoped for a different result.
Germany is the most populous country in the 28-nation EU and has its biggest economy.
Leaders in past months have been emphasizing that while it was up to the British people to decide, Germany wanted Britain to remain in the European Union.
Switzerland, which is not in the European Union, has set up a helpline for its citizens with questions over the British exit.
The Swiss government on Friday assured its citizens that despite the vote, "currently applicable rules for Swiss citizens and businesses remain valid for the time being."
But the government says it was adding additional staff to help field questions from its citizens. It says it plans to keep the hotline up around the clock, seven-days a week as needed.
French President Francois Hollande's said that he profoundly regrets the British vote to leave the European Union, but that the union must make changes in order to move forward.
French far-right leader Marine Le Pen, who is more popular in polls than Hollande, called Friday for a similar anti-EU referendum in France.
French Foreign Minister Jean-Marc Ayrault said that he was "sad for the United Kingdom". "
Ayrault said Europe would continue, but it must react and rediscover the confidence of its peoples.