BRUSSELS -- The European Union on Thursday urged Iran to respect the international agreement curbing the Islamic Republic's nuclear ambitions, and added that the bloc aims to continue trading with the country despite U.S. sanctions.

The EU and major European powers -- Britain, France and Germany -- also said that they "note with great concern the statement made by Iran concerning its commitments" to the nuclear deal, stressing that they "reject any ultimatums" coming from Tehran.

The joint statement came as the bloc struggles to preserve the 2015 nuclear deal with Iran, a day after a new deadline from Tehran on finding a solution to make up for last year's unilateral U.S. withdrawal from the accord and re-imposed U.S. sanctions on Iran.

"We remain fully committed to the preservation and full implementation" of the deal, endorsed by the UN Security Council, said the EU statement.

The Trump administration pulled America out of the 2015 deal a year ago, saying it does nothing to stop Iran from developing missiles or destabilizing the Middle East. The Europeans insist that the pact is an important pillar of regional and global security and was never meant to address those other issues.

Iranian President Hassan Rouhani said in a televised address Wednesday that signatories to the deal now have 60 days to come up with a plan to shield his country -- already labouring under economic hardship -- from the sanctions imposed by President Donald Trump.

As the sanctions bite, domestic pressure is increasing on Rouhani to demonstrate that Iran can still benefit from an agreement based on providing it with economic opportunities in exchange for limiting nuclear development.

"Iran must remain in this agreement and we must do everything we can to ensure that it stays in," French President Emmanuel Macron told reporters at an EU summit in Romania, where leaders were to discuss the standoff.

Amid the heated rhetoric from Tehran and Washington, Macron urged the agreement's signatories not to "get caught up in any escalation" and to "jointly watch over our collective security."

In their statement, the EU powers said they "regret the re-imposition of sanctions" by the U.S. and remain "determined to continue pursuing efforts to enable the continuation of legitimate trade with Iran."

The Europeans have set up a complicated barter-type system to skirt direct financial transactions with Iran and so evade possible U.S. sanctions. The workaround, dubbed INSTEX, is not yet operational as Iran has not completed its part of the scheme.

The bloc said it plans to push ahead with "the operationalization of the special purpose vehicle 'INSTEX'."

The EU has also introduced a so-called "blocking statute" protecting European companies from the effects of U.S. sanctions, but many international corporations do more business in the United States than in Iran and have already severed ties there rather than risk running afoul of Washington.

In a message implicitly directed at the U.S. administration, the EU powers said "we call on countries not party to the (deal) to refrain from taking any actions that impede the remaining parties' ability to fully perform their commitments."

Despite the heated rhetoric, the Europeans insist that only the International Atomic Energy Agency can judge whether Iran remains in compliance with the nuclear agreement. More than a dozen reports have shown that Tehran is respecting it so far. A new report is due at the end of May.

"So far we have seen Iran fully compliant with all its nuclear-related commitments," EU foreign policy chief Federica Mogherini said at the summit. The deal, she said, "is a matter of security for us and for the entire world."

The crisis with Iran comes at a sensitive moment in the wider Middle East. On Sunday, the White House said it dispatched the aircraft carrier USS Abraham Lincoln and B-52 bombers to the Persian Gulf over what it described as a new threat from Iran. Israel, which has conducted pre-emptive bombings of nuclear facilities in Iraq and Syria, has vowed to never allow Iran to obtain an atomic weapon.

The USS Abraham Lincoln on Thursday passed through the Suez Canal on its way to the Persian Gulf, according to Mohab Mameesh, the canal's authority chief. The state MENA news agency said the U.S. defence attache in Cairo, Gen. Ralph Groover, travelled to the Suez Canal area to check on the status of the U.S. warship.

Also on Thursday, the official IRNA news agency said Britain's Director General for Political Affairs Richard Moore met with Iranian officials in Tehran. The report said he had "useful talks" with the Iranian side on issues such as "regional security" and bilateral relations. It did not elaborate.

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Associated Press writers David Rising in Berlin and Noha ElHennawy in Cairo contributed to this report