European Union nations have thrown their diplomatic weight behind the unravelling Iran nuclear deal, trying to rescue the pact from collapsing under US pressure.
The 28 EU foreign ministers insisted recent Iranian actions surpassing uranium enrichment thresholds set by the 2015 deal did not necessarily condemn the whole agreement.
"We note that technically all the steps that have been taken - and that we regret have been taken - are reversible. So we hope and we invite Iran to reverse the steps," said EU foreign policy chief Federica Mogherini on Monday.
"The deviations are not significant enough to think that Iran has definitively broken the agreement," said Spanish Foreign Minister Josep Borrell, who is in line to succeed Mogherini this (northern) autumn.
The EU currently has few direct measures for offsetting US economic sanctions against Tehran that have crippled the country's economy, and the bloc faces US threats to target any EU companies that attempt to trade with Iran.
Noting that Iran was "still a good year away" from potentially developing a nuclear bomb, British Foreign Secretary Jeremy Hunt said there was still a "small window to keep the deal alive".
Even if Britain, France, Germany and the rest of the EU held out a helping hand to Iran, the diplomatic puzzle was made more difficult on Monday when France's foreign ministry said a researcher with dual French-Iranian nationality had been arrested in Iran.
It said the French government was seeking information about Fariba Adelkhah and consular access to her "without delay" but added there has been "no satisfactory response to its demands as of today".
Iranian opposition websites based abroad have said Abdelkhah disappeared in June.
And while the EU nations were looking to de-escalate tensions in the Persian Gulf region, they also put the blame on the Trump administration for quitting the deal last year, imposing sanctions and trying to keep European nations from trading with Iran.
French Foreign Minister Jean-Yves Le Drian said that Iran's recent moves to surpass mutually agreed limits from the deal were only "a bad reaction following a bad decision - which was the US decision to withdraw from the accord and put sanctions into place".
China, another signatory to the global agreement, said US pressure was the root cause of recent developments and called on the Trump administration to step in and fix the diplomatic quagmire.
Chinese foreign ministry spokesman Geng Shuang said it was "better for the one who made the trouble to fix it".
Facing economic hardship, Iran had called on the other parties to the agreement - Germany, France, Britain, China, Russia and the EU - to come up with enough economic incentives to effectively offset the US sanctions.
While the Europeans were still hoping to find an amicable solution, the US instead called on them to turn their backs on Iran.
Gordon Sondland, the US ambassador to the EU, told the BBC that "our European friends should join the US in unequivocally condemning Iran's actions with respect to their malign activities, not just in the Strait of Hormuz but throughout the world".
Tehran said Sunday it was ready to negotiate with the US if Washington lifts the economic sanctions.
President Hassan Rouhani's official website quoted him as saying, "The moment you stop sanctions and bullying, we are ready to negotiate."
Australian Associated Press