U.S. President Donald Trump's new threats will have no effect on Iran, the country's top negotiator Mohammad Baqer Qalibaf said in comments carried by state media on Sunday.
"If you fight, we will fight, and if you come forward with logic, we will deal with logic," said Qalibaf, who led his country's delegation to the talks along with Foreign Minister Abbas Araqchi.
Trump said on Sunday the U.S. Navy would start blockading the Strait of Hormuz, raising the stakes after marathon talks with Iran failed to reach a deal to end the war, jeopardizing a fragile two-week ceasefire.
Qalibaf blamed the U.S. for not winning Tehran's trust, despite his team offering "forward-looking initiatives".
Iranian officials said talks fell apart over two or three key issues, blaming what they called U.S. overreach. Qalibaf, who noted progress in the negotiations, said it was time for the United States "to decide whether it can gain our trust or not."
Trump also said in a post on Truth Social that the U.S. would take action against every vessel in international waters that had paid a toll to Iran, and begin destroying mines that he said the Iranians had dropped in the strait, a choke point for about 20% of global energy supplies that Iran has blocked.
"No one who pays an illegal toll will have safe passage on the high seas," Trump wrote, adding: "Any Iranian who fires at us, or at peaceful vessels, will be BLOWN TO HELL!"
Iran's Revolutionary Guards responded with a statement warning that military vessels approaching the strait will be considered a ceasefire breach and dealt with harshly and decisively, underlining the risk of a dangerous escalation.
Six weeks of fighting has killed thousands, roiled the global economy and sent oil prices soaring as Iran prevented traffic through the strait.
In an interview with Fox News after his post about the strait, Trump said that he believed Iran would continue to negotiate and called the weekend discussions "very friendly".
"I do believe they're going to come to the table on this, because nobody can be so stupid as to say, 'We want nuclear weapons,' and they have no cards," Trump told Fox News from his golf course near Miami, Florida.
Trump also said that NATO allies, whom he has criticized for failing to back the war he launched along with Israel on February 28, wanted to help with the operation in the strait.
There was no immediate comment from Washington's allies.
The weekend talks in Islamabad, which followed the announcement of a ceasefire last Tuesday, were the first direct U.S.-Iranian meeting in more than a decade and the highest-level discussions since the 1979 Islamic Revolution.
"The bad news is that we have not reached an agreement, and I think that's bad news for Iran much more than it's bad news for the United States of America," said Vice President JD Vance, who headed the U.S. delegation.
A U.S. official said Iran had rejected Washington's call for an end to all uranium enrichment, the dismantling of all major enrichment facilities and the transfer of highly enriched uranium. The two sides also failed to reach agreement on the U.S. demand that Iran cease funding for Hamas, Hezbollah and the Houthis as well as fully open the strait, the official added.
Iran's President Masoud Pezeshkian, who discussed the talks in a call with Russian President Vladimir Putin, said Tehran wanted "a balanced and fair agreement".
"If the United States returns to the framework of international law, reaching an agreement is not far off," he told Putin, Iranian state media reported.
