BRUSSELS -- European Union nations were throwing their diplomatic weight behind the unraveling Iran nuclear deal Monday, trying to rescue the pact from collapsing under U.S. pressure.

The EU currently has few direct measures for offsetting U.S. economic sanctions against Tehran crippling the country's economy, and the bloc faces U.S. threats to target any EU companies attempting to trade with Iran. Nevertheless, EU foreign ministers insisted recent Iranian actions surpassing uranium enrichment thresholds set by the 2015 deal did not necessarily condemn the whole agreement.

"The deviations are not significant enough to think that Iran has definitively broken the agreement," Spanish Foreign Minister Josep Borrell said of Iran's recent moves to go beyond the enrichment limits.

Noting 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 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 deescalate 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 Iran's recent moves to surpass mutually agreed limits from the deal were only "a bad reaction following a bad decision -- which was the U.S. decision to withdraw from the accord and put sanctions into place."

China, another signatory to the global agreement, said U.S. 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 U.S. sanctions.

While the Europeans were still hoping to find an amicable solution, the United States instead called on them to turn their backs on Iran.

Gordon Sondland, the U.S. ambassador to the EU, told the BBC "our European friends should join the U.S. in unequivocally condemning Iran's actions with respect to their malign activities, not just in the Strait of Hormuz but throughout the world."

But EU foreign ministers first and foremost want to get Iran to respect the terms of the deal again. At their regular monthly meeting, the EU foreign ministers sought to drum up further support for the bloc's proposed barter-type system to trade with Tehran and get around possible U.S. sanctions. Ten nations are already on board with the idea, and Borrell said Spain was among them.

Tehran said Sunday it was ready to negotiate with the United States 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."

A day earlier, Britain's top diplomat said the U.K. would facilitate the release of a seized Iranian tanker if Iran can provide guarantees the vessel would not breach European sanctions on oil shipments to Syria.