"But we believe this is a healthy step forward", State Department spokesman Ned Price said.
The statement comes as Iranian Foreign Minister Javad Zarif announced earlier on Friday that the United States would not take part in talks on the JCPOA, scheduled for next week in Vienna.
The announcement followed a virtual meeting of Iran and signatories other than the United States on Friday. The Biden administration and Iran have differed on any conditions for that to happen, including the timing of the lifting of US sanctions against Iran.
Participants will meet in the Austrian capital "to clearly identify sanctions lifting and nuclear implementation measures, including through convening meetings of the relevant expert groups", a statement said.
Israeli officials, including Prime Minister Benjamin Netanyahu, have already begun voicing opposition to the Biden administration's desire to rejoin the deal, putting Jerusalem and Washington at odds on the issue.
U.S. President Joe Biden's predecessor, Donald Trump, withdrew from the deal in 2018 and reimposed U.S. sanctions on Iran, prompting Tehran to violate some of the pact's nuclear restrictions in retaliation. He stressed that a meeting between Iran and the U.S. was "unnecessary" at this point.
Iran has insisted that the United States must act first on removing the Trump sanctions, which include a unilateral effort to stop all its oil exports, before it will roll back measures away from compliance that it had taken as a protest.
But Tehran says Washington has to lift global sanctions that were reimposed by Trump before it will make any moves to get back in line, and is refusing to hold direct negotiations with the US.
US officials had no immediate public comment, but Washington on Thursday welcomed the news that the Europeans would be meeting with the Iranians to try to get talks going again.
The U.S. and Iran have been in a standoff over reviving the nuclear deal.
Russia's ambassador to global organizations in Vienna, Mikhail Ulyanov, said that "the impression is that we are on the right track, but the way ahead will not be easy and will require intensive efforts".
Earlier this month, Iranian supreme leader Ayatollah Ali Khamenei said his country may return to full compliance of the JCPOA if Tehran deems Washington has honoured its commitments.
He stated that the agreements "will ultimately allow Iraq to develop its energy self-sufficiency and, we hope, to end its reliance on Iran".