Iran's Foreign Ministry rejects any "step-by-step" lifting of sanctions imposed against it, the state-funded Press TV quoted the ministry's spokesman as saying on April 3.
"The definitive policy of the Islamic Republic of Iran is the lifting of all U.S. sanctions," Foreign Ministry spokesman Saeed Khatibzadeh said in an interview with Press TV.
U.S. State Department deputy spokeswoman Jalina Porter said on April 2 that talks next week in Vienna on reviving the 2015 nuclear deal will focus on "the nuclear steps that Iran would need to take in order to return to compliance" with that agreement.
The United States unilaterally pulled out of the nuclear agreement in 2018 under former President Donald Trump, who reimposed crippling economic sanctions on Tehran.
Iran reacted by gradually reducing its commitments under the deal, including higher uranium enrichment.
U.S. President Joe Biden has signaled his readiness to revive the accord but his administration says Iran must first return to its nuclear commitments.
The head of Iran's Atomic Energy Organization, Ali Akbar Salehi, said on April 2 that Tehran was optimistic about the course of the negotiations in Vienna on April 6, during which Tehran and Washington will negotiate indirectly.
"We are about to get out of the impasse," Salehi said in a conversation on the social-media app Clubhouse.
Earlier, U.S. State Department spokesman Ned Price called the resumption of negotiations, scheduled in Vienna, "a healthy step forward."
But Price added, "These remain early days, and we don't anticipate an immediate breakthrough as there will be difficult discussions ahead."
Price said next week's talks will be structured around working groups that the European Union was forming with the remaining participants in the accord, including Iran.
The United States, like Iran, said it did not anticipate direct talks between the two nations now. Price said the United States remains open to that idea.
"This is a first step," Biden Iran envoy Rob Malley said on Twitter on April 2. He said diplomats were now "on the right path."
French Foreign Minister Jean-Yves Le Drian said in a statement on April 3 that he has called on Iran to show a constructive stance in next week's talks in Vienna.
Following a call with his Iranian counterpart,Mohammad Javad Zarif, Le Drian said in a statement that he had asked Iran to refrain from further violations of current nuclear commitments to aid discussions.
"I encouraged Iran to be constructive in the discussions that are set to take place," Le Drian said. "They are meant to help identify in the coming weeks the steps that will be needed in order to return to full compliance with the nuclear deal."