Iran's Foreign Minister, Hossein Amir-Abdollahian, said on Sunday that Washington is "imposing new conditions" in the negotiations to restore the 2015 nuclear agreement, reported the AFP news agency.
"On the issue of lifting sanctions, they (the Americans) are interested in proposing and imposing new conditions outside the negotiations," said Amir-Abdollahian.
"In the last two or three weeks, the American side has made excessive demands that contradict some paragraphs of the text," he added.
"The Americans keep talking about the need for direct negotiations, but we have not seen the benefit of direct talks with the United States," Amir-Abdollahian said.
"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".
Iran has gradually scaled back its compliance with the 2015 deal, in response to former US President Donald Trump’s withdrawal from the agreement in May of 2018, but has held several rounds of indirect talks with the US on a return to the agreement.
Negotiations nearly reached completion last month before Moscow demanded that its trade with Iran be exempted from Western sanctions over Ukraine, throwing the process into disarray.
Among the key sticking points is Tehran's demand to delist the Revolutionary Guards from a US terror list.
Last month it was reported that the Biden administration is considering removing terrorism sanctions from the IRGC as part of negotiations to restore the 2015 Iran nuclear deal.
However, The Washington Post reported on Friday that the Biden administration plans to reject the Iranian demand.
Last week, the Pentagon's top general said he was opposed to removing the elite Quds Force of Iran's Revolutionary Guards from the US terror group list.
"In my personal opinion, I believe the IRGC Quds Force to be a terrorist organization, and I do not support them being delisted from the foreign terrorist organization list," Joint Chiefs Chairman General Mark Milley told a congressional hearing.