PARIS – After President Donald Trump announced Tuesday that the United States would withdraw from the Iran nuclear accord, key U.S. allies and others voiced concern about the fallout but vowed to salvage the deal.

Chief among the critics was French President Emmanuel Macron, who was Europe's leading emissary to Washington in efforts to defend the deal and who has sought to cultivate a strong personal rapport with Trump.

Macron spoke on the phone with his American counterpart earlier Tuesday about "peace and stability in the Middle East." But after Trump's announcement, the French president immediately expressed his disappointment on social media and later joined German Chancellor Angela Merkel and British Prime Minister Theresa May in a joint statement noting their "regret and concern."

"Together, we emphasize our continuing commitment to the JCPOA," their statement read, using the abbreviation for the deal's official name, the Joint Comprehensive Plan of Action.

For many in Europe, Trump's decision was no surprise: He has been a longtime critic of the Iran agreement — a signature foreign policy achievement of the Obama administration — which placed curbs on Iran's nuclear program in exchange for lifting international sanctions.

Inspectors from the U.N. nuclear watchdog agency have said Iran is in compliance with the accord. But Trump has taken issue with provisions that lift some restrictions on Iran's nuclear efforts in years to come, and he never accepted the premise that it was the best near-term strategy to prevent a nuclear-armed Iran.

An American exit threatens the entire accord. Tehran was lured to the bargaining table by the prospect of an injection of international investment to buoy its economy. A renewal of sanctions would give the country's leaders little reason to adhere to their part of the deal.

"The pressure is mounting because there are forces in Iran who never liked the agreement and who claim that there is a feeling that the Iranian side delivered and that our side didn't deliver," a senior European diplomat said, speaking on the condition of anonymity to discuss sensitive considerations as Trump mulled what to do about the deal.

But after Trump's remarks Tuesday, the co-signatories of the agreement — France, Britain, Germany, Russia, China, the European Union and Iran ­— said they would seek to save it.

Iranian President Hassan Rouhani ordered his diplomats to negotiate with their European, Russian and Chinese counterparts, though he threatened that Iran would commence unlimited uranium enrichment if the continued negotiations do not yield results within several weeks.

The Europeans, likewise, insisted on fighting to keep the deal in force.

"We urge the U.S. to ensure that the structures of the JCPOA can remain intact, and to avoid taking action which obstructs its full implementation by all other parties to the deal," Macron, Merkel and May said in their statement. "After engaging with the U.S. Administration in a thorough manner over the past months, we call on the U.S. to do everything possible to preserve the gains for nuclear non-proliferation brought about by the JCPOA, by allowing for a continued enforcement of its main elements."