"We urge Iran to return to the negotiations soon," State Department spokesman Ned Price told reporters.

"If President Raisi is genuine in his determination to see the sanctions lifted, well that is precisely what's on the table in Vienna," he said.

"We hope that Iran seizes the opportunity now to advance diplomatic solutions," Price said.

He was referring to months of fruitless indirect talks in the Austrian capital on reviving the 2015 nuclear accord trashed by former president Donald Trump.

Price reiterated that the Biden administration, despite concerns with Iran, saw the accord as key to securing "permanent and verifiable limits on Iran's nuclear program."

Price said that the proposal to end sweeping sanctions in return for compliance with the deal would not last "indefinitely."

"For us, this is an urgent priority, knowing the issues that are at play," Price said. "We hope that the Iranians treat it with the same degree of urgency."