Iran said on Monday it will only return to Vienna in order to finalise an agreement to save the 2015 nuclear deal with world powers.
Tehran insisted that the last steps are totally dependent on the United States.
Iran and the US have been engaged in long-running indirect negotiations in the Austrian capital to revive the deal, known formally as the Joint Comprehensive Plan of Action (JCPOA), with Britain, China, France, Germany, and Russia.
"We will not be going to Vienna for new negotiations but to finalise the nuclear agreement," foreign ministry spokesman Saeed Khatibzadeh told reporters in Tehran.
However, Iran admitted that there were still outstanding issues, which the Islamic Republic said they are waiting for Washington to settle.
"At the moment, we do not yet have a definitive answer from Washington," Khatibzadeh said.
"If Washington answers the outstanding questions, we can go to Vienna as soon as possible."
