In the capital's affluent north, motorists played loud music from car stereos and young people blew South African-style 'vuvuzela' horns, scenes that Tehran normally witnesses only when the country qualifies the football World Cup. A woman in Vanak Square in north Tehran told Reuters by phone that people were buying sweets and handing them out on the streets.
A news conference announcing the deal achieved in marathon talks in Vienna was broadcast live on state TV. So was a speech by U.S. President Barack Obama, an event almost inconceivable until recent months. Iranians gathered around TVs at home and in shops to watch it.
"This is a first step to becoming a friend with the world," Bahar Ghorbani, 36, a housewife who lives in Isfahan said.
"I think the biggest achievement of the nuclear deal is the victory of logic and dialogue over warmongering and violence," she said, contacted over Facebook.
"Now people can see the result of their votes," Behrouz Janfada, head of an IT department at an education institute, told Reuters from Tehran. "Rouhani promised to solve the nuclear issue in his electoral campaign, people elected him and he managed to save Iran from the sanctions and the threat of a war. That brings hope, and the feeling that you have a say."
But not everyone was keen to party. Nassim, a 42-year-old graphic designer who said he struggled to make ends meet as an artist, said he would not celebrate until he saw improvements in his own life.
"I didn't go to the streets. It's like World Cup celebrations. What's in it for me?" he said. "Tehran's streets are full of expensive convertible cars. That's the effect of sanctions. Those who had money got richer, and the poor are still poor and will remain poor."