"On the issue of lifting sanctions, they (the Americans) are interested in proposing and imposing new conditions outside the negotiations," Amir-Abdollahian said.
"In the last two or three weeks, the American side has made excessive demands that contradict some paragraphs of the text," he added, according to IRNA.
Iran has been engaged for a year in negotiations with France, Germany, Britain, Russia and China directly, and the United States indirectly in the Austrian capital to revive the deal, known formally as the Joint Comprehensive Plan of Action (JCPOA).
"The Americans keep talking about the need for direct negotiations, but we have not seen the benefit of direct talks with the United States, based on our surveys and the viewpoint that the Americans hold,” Amir-Abdollahian said.
The 2015 agreement gave Iran sanctions relief in exchange for curbs on its nuclear program. The US unilateral withdrawal from the accord in 2018 under then-president Donald Trump and the reimposition of tough economic sanctions prompted Iran to begin rolling back on its own commitments in retaliation.
"We seek the lifting of sanctions, but with dignity and with a lasting agreement," the foreign minister said, adding that "Iran has stood and will stand by its red lines".
The Vienna talks aim to bring back the US to the nuclear deal, including through the lifting of sanctions on Iran, and to return Iran to full compliance with its commitments.
They have been paused since March 11 after Russia demanded guarantees that Western sanctions imposed following its February 24 military operation in Ukraine would not damage its trade with Iran. Days later, Moscow said it had received the necessary guarantees.
"During my visit to Moscow, we agreed with the Russian side that if we reached an agreement in Vienna, Russia would not be an obstacle," Amir-Abdollahian said.
"We were close to concluding technical discussions with the three European countries, but at the same time we faced the crisis and the war in Ukraine," he added.
Talks had progressed most of the way toward reviving the deal, with different parties pointing to the "final phase", but pending issues are still unresolved.
Among the sticking points is Tehran’s key demand to remove the Islamic Revolution Guards Corps from the US list of “terrorists”.
Amir-Abdollahian said US President Joe Biden should lift some sanctions on Iran to show his goodwill toward reviving the JCPOA.
"If Biden has intentions to lift sanctions and return to the nuclear deal, he should issue an executive order to show his goodwill instead of applying sanctions on natural and legal persons in Iran," the foreign minister said.
He underscored that Iran has demanded neither loans nor money from Americans, but rather asked for the release of its own public assets.
"On multiple occasions, we have told Americans they should bring forward one or two practical points prior to any agreement, for example by releasing some of Iran's assets withheld in foreign banks," Amir-Abdollahian added.
“We plainly informed the American side not to stonewall, sabotage and delay the agreement. If our red lines are observed and we see a good, strong and lasting agreement before us, there is no doubt for the Iranian side to remain in the deal and for all parties to return to their commitments under the JCPOA,” Amir-Abdollahian said.
“The path to diplomacy is still open. Of course, the three European countries in addition to China and Russia have criticized the latest excessive demands of Americans, which have delayed the conclusion of an agreement. They raise some of the issues in their talks with the American side. They sometimes share our opinion and state that the US approach is inconsistent with the spirit of cooperation being pursued in Vienna talks,” he said.