“Considering the recent actions and statements by the United States and three European powers, Iran does not consider this the time to hold an informal meeting with these countries, which was proposed by the EU foreign policy chief,” Foreign Ministry spokesman Saeed Khatibzadeh said, according to Iranian media. 

The United States said it was disappointed but remained ready to “re-engage in meaningful diplomacy” and would consult with the other major powers to seek a way forward. 

Iranian officials had said Tehran was studying a proposal by European Union foreign policy chief Josep Borrell to hold an informal meeting with other parties to the nuclear pact and the United States, which reimposed sanctions on Iran after then-President Donald Trump quit the deal in 2018. 

The new administration of President Joe Biden has said it is ready to talk to Iran about both nations resuming compliance with the accord, which scrapped broad economic sanctions against Iran in return for curbs intended to prevent it from acquiring nuclear weapons - something Iran says it does not want. 

But the parties cannot agree who should make the first move. Iran says the United States must lift sanctions, while Washington says Tehran must return to compliance with the deal, which Iran has been progressively breaching since 2019. 

A White House spokeswoman said Washington remained keen to achieve a “mutual return to compliance” with the deal. 

She said it would consult with the major powers that are also parties to the deal - Britain, China, France, Germany and Russia - on the best way forward. 

NOT ‘THE END OF THE ROAD’ 

One senior U.S. source said Iran’s rejection was simply part of the diplomatic process. 

Separately, a senior U.S. official said the United States was not wedded to any particular format for talks. 

“We don’t think that this is the end of the road. It’s unfortunate ... that the Iranians said: ‘No,’ but we’ll be open to other ideas,” said the senior U.S. official. 

“If they want us to consider some other format, we’re not going to be sticklers for format,” he added. 

Earlier, Iran’s nuclear chief urged the International Atomic Energy Agency’s (IAEA) 35-nation Board of Governors not to endorse a U.S.-led push to criticise Tehran’s decision to scale back its cooperation with the U.N. nuclear watchdog. 

“If the IAEA’s Board of Governors adopts a resolution against Iran, we will show an appropriate reaction,” Ali Akbar Salehi said, according to the Iranian state news agency, IRNA. 

In a position paper seen by Reuters and sent to other IAEA member states before the board’s quarterly meeting this week, Tehran threatens to end a deal struck with the IAEA a week ago temporarily maintaining some monitoring of its activities. 

Diplomats said it was unclear whether the board would adopt a resolution. 

Last Tuesday, Tehran stopped implementing the so-called Additional Protocol, which had enabled the IAEA to carry out snap inspections at undeclared locations. 

But under the Feb. 21 agreement, Tehran agreed to maintain the recording of extra data as specified by the 2015 deal for up to three months, and to let the IAEA access it at the end if sanctions were lifted. 

Khatibzadeh said there was no need for a “negotiation or a resolution” by the IAEA board of governors for the United States to “end its illegal and unilateral sanctions and return to its commitments.”