Russia calls on US to 'be more active' to revive Iran deal
"It seems evident they should be more active" in "resolving all issues related" to the accord, Lavrov told reporters at the United Nations in New York.
Lavrov added that he hoped negotiations in Vienna among Iran, Russia, China, France, Britain and Germany would resume "as soon as possible."
The talks, brokered by the Europeans, seek the return of the United States to the 2015 agreement trashed by former president Donald Trump - as well as Iran's return to full compliance.
Trump pulled America out in 2018, reinstating sanctions on Iran that Washington had lifted as part of the agreement.
Since then, Tehran has also retreated from many of its commitments.
Trump's successor Joe Biden has indicated he wants to return to the deal, but his administration has expressed impatience at the stalled talks.
Discussions between Iran and the remaining five parties aimed at reviving the deal began in Vienna in April but have been suspended since June, when ultraconservative Ebrahim Raisi was elected president.
Hopes of reviving the deal were kept alive earlier this month when Iran agreed to a new compromise with the UN nuclear agency on the monitoring of its nuclear facilities.
Iran's foreign minister, Hossein Amir-Abdollahian, said on Friday the talks would resume "very soon," but the United States said Tehran had not been specific about the timeframe.
"We are reviewing the Vienna negotiations files currently and very soon Iran's negotiations with the four plus one countries will recommence," Hossein Amir-Abdollahian told reporters in New York, referring to Britain, France, Russia, China and Germany.
"We see a constructive type of negotiation that will lead to tangible verifiable results in the foreign policy of the new government in Iran," the foreign minister added during a press conference on the sidelines of the UN General Assembly.
Asked what Amir-Abdollahian meant by "very soon," a senior Iranian official said on condition of anonymity that "it can mean a few days, it can mean a few weeks."
"As soon as we finish the review process, without any time to be wasted, we shall return to the negotiations table," the official said.
State department spokesman Ned Price said the US had heard the "message" of "soon and very soon" all week at the UN.
"But we have up until this point not received clarity on what precisely that means," he told reporters.