President Hassan Rouhani on Tuesday ruled out holding any bilateral talks with the United States and threatened to further cut Iran's commitments to a nuclear deal within days.
In an address to parliament, Rouhani said any dialogue with the US would have to fall within the framework of the group of major powers that agreed a landmark nuclear deal with Tehran in 2015.
Rouhani also said Iran was ready to further reduce its commitments to the accord "in the coming days" if current negotiations with European nations yield no results by Thursday.
Tehran and Washington have been at loggerheads since May last year when US President Donald Trump unilaterally withdrew from the nuclear deal and began reimposing crippling sanctions.
The arch-foes were on the cusp of confrontation in June when Iran downed a US drone and Trump ordered retaliatory strikes before cancelling them at the last minute.
France has been leading efforts to calm the situation, with President Emmanuel Macron expressing hope during G7 talks in late August of organising a meeting between Rouhani and Trump.
"Maybe there has been a misunderstanding. We've said it several times and we repeat it -- there has been no decision to hold bilateral talks with the US," said Rouhani.
"In principle, we don't want bilateral talks with the United States," he was quoted as saying on the official government website.
"If the United States lifts all sanctions, it would be possible to talk (to them) during 5+1 meetings as in the past," he said, referring to the powers involved in negotiating the 2015 deal.
"We have received several proposals (to have talks with the United States) and our answer has always been negative."
Iran has hit back with countermeasures in response to the US withdrawal from the deal, which gave it the promise of relief from sanctions in return for curbs on its nuclear programme.
It has already increased its uranium enrichment and stockpiles, and Rouhani said Tuesday a "third step will be enacted in the coming days" unless the remaining parties to the deal honour their own commitments.
"If by Thursday these negotiations yield no results, we will announce the third step of the reduction of our commitments," he said.
But the president stressed the Iranian countermeasures were reversible.
"Our steps have been taken in such a way that it doesn't take much time to get back to the starting point," he said.
Rouhani voiced regret over the failure of European nations to fulfil pledges they made during negotiations.
"Unfortunately after the US betrayal... the Europeans haven't acted on their commitments or couldn't... in some cases they cold have acted but did not," he said.
"What we are asking of the other countries is that they continue to buy our oil.
"We can continue negotiations even after the third step," he added.
Rouhani has had a series of phone calls with Macron in recent weeks aimed at salvaging the nuclear deal.
The French president has been trying to convince the United States to offer Iran some sort of relief from sanctions it has imposed on the Islamic republic since pulling out of the deal.
A conservative Iranian lawmaker said Macron had proposed offering Iran a $15-billion credit line on condition it returns to the fold.
"Macron has proposed Iran stop its third step for now in exchange for this sum, and maybe retreat from its first and second steps to the initial situation," said Ali Motahari, quoted late Sunday by Iran's Tasnim news agency.
The 2015 deal was agreed between Iran and the so-called 5+1 -- UN Security Council permanent members Britain, China, France, Russia and the United States plus Germany.