Iran insists it has the option of resuming industrial-scale enrichment following the United States exit from the deal.
They are seeking to ring-fence trade with Iran against new USA financial sanctions to dissuade Tehran from quitting the deal.
Since then, Khamenei and other Iranian officials have been on the attack, threatening to increase uranium enrichment.
Tensions between Washington and Tehran were reignited after Trump pulled the United States out of the controversial Iran nuke deal, which he claimed would not stop the country from developing deadly warheads.
"However, at this particularly critical juncture, they will not contribute to build confidence in the nature of the Iranian nuclear programme", Maja Kocijancic, spokeswoman for European Union diplomatic chief Federica Mogherini, told AFP. He also said Iran could no longer have any dealings with the US.
The Europeans have proposed hammering out a supplementary deal with Tehran covering its ballistic missile programme as well as its interventions in countries such as Lebanon, Syria, Iraq and Yemen.
The 2015 deal limited Iran to enriching uranium only to 3.67%, far below the roughly 90% threshold of weapons-grade material.
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Yisrael Katz's spoke out after Israeli Prime Minister Benjamin Netanyahu began visiting European leaders to discuss Iran's regional involvement and nuclear programme, both seen by the Jewish state as grave threats.
Israel maintains that Iran duped the West into a one-sided deal and plans to use the break from sanctions to build up its financial reserves before returning to full-scale enrichment of uranium for future nuclear weapons.
"The aim to prevent Iran from developing any kind of nuclear capacity was always the foundation of global policy on Iran", Israel's ambassador to Germany, Jeremy Issacharoff, told AFP ahead of the visit.
Israeli Prime Minister Benjamin Netanyahu was met by scores of protesters calling for him to be tried as a war criminal on Tuesday at the Paris stop of his tour of European capitals.
In a letter from Iranian Foreign Minister Mohammad Javad Zarif to his counterparts last week, he asked "the remaining signatories and other trade partners" to "make up for Iran's losses" caused by the U.S. exit, if they sought to save the deal.
The European powers are trying to come up with a package to ring-fence trade with Iran against renewed US financial sanctions to dissuade Tehran from quitting the accord.
PSA followed in the footsteps of French oil giant Total, whose chief executive said last week that the chances of winning exemptions to the U.S. sanctions were "very slim".