"We remain ready to engage in meaningful diplomacy to achieve a mutual return to compliance" in a 2015 nuclear deal, State Department spokesman Ned Price told reporters.

"We are not dogmatic about the form and the format of those talks."

President Joe Biden's administration supports a return to the 2015 nuclear accord from which former president Donald Trump bolted and on February 18 said it was willing to meet with Iran in a meeting proposed by the European Union.

The meeting would involve the other signatories of the 2015 agreement -- Britain, China, France, Germany and Russia.

But Iran said Sunday that the timing was not "suitable" as it remained insistent that the United States first lift sanctions imposed by Trump in violation of the agreement.

"As we have made clear, the United States is prepared to meet with Iran to address the way forward on a mutual return to compliance," Price said.

"We're not dogmatic about what form that takes; what we are dogmatic about is the underlying commitment," he said, "that this administration broadly has that Iran cannot be allowed to acquire a nuclear weapon."

Iran has insisted that sanctions imposed by Trump, including a sweeping ban on its oil exports, should be removed before it reverses steps out of nuclear compliance that it took as protest measures.