The sides have reached "a clear text" about all issues and what remains needs political decision from all sides, Saeed Khatibzadeh told reporters at his weekly press briefing.
Iran and 4+1 have been holding talks in Vienna, Austria, since about three months ago to reach agreement on removal of anti-Iran sanctions and possible return of the US to the Joint Comprehensive Plan of Action (JCPOA) from which Washington withdrew unilaterally in May, 2018.
As the spokesman said, if this political decision is taken, the next talks can be the last round.
In a related development, Iran's top negotiator in Vienna Abbas Araghchi said on Monday that negotiations have gone a long way, but the remaining part of the road was not easy to pass.
Touching upon the June 18 presidential election in Iran, the spokesman said 48 presidents, parliament speakers and senior figures have extended congratulations to the president-elect, Ebrahim Raisi, during the past 48 hours.
Participation of people in the election in and out of the country carried positive messages, Khatibzadeh underlined.
With near 18 million votes out of about 29 millions, Raisi won the 13th presidential election. About 60 million Iranians were eligible to vote.
Asked whether agreement on revival of the JCPOA has been postponed to tenure of next Iranian government, the spokesman said such reports and speculations are far from reality.
Iran's policy does not intend to delay the possibility of lifting of the sanctions, Khatibzadeh noted.
And it is Supreme Leader's policy which is being continued by the negotiating team, he added.
Asked if there is possibility of reaching agreement in Vienna during President Rouhani's tenure, the spokesman said that diplomats are optimistic about the issue; meanwhile, it is too soon to judge as the political decisions to be taken by all sides are of paramount importance.
"The text has no ambiguities."
About the recent remarks made by US national security adviser, Jake Sullivan, the spokesman said that never will talks be held on a new JCPOA.
Iran will not be satisfied with anything more or less than JCPOA, he stressed.
Turning to the issue of Afghanistan, Khatibzadeh said that Iran follows up developments in Afghanistan with concern.
He went on to say that Tehran invites all to relieve tension, be committed to intra-Afghan peace talks, and respect rights of minorities.
About new government's policy on the JCPOA and the Zionist media's approach to the issue, the spokesman said that the Zionist media have nothing to do but damage the face of presidents elected by the Iranian nation.
All will see that Iran's principled policies will continue [during Raisi's term], he added.
About whether Iran has asked the US for guarantee, the spokesman said that the issue is basically correct but the details cannot be discussed openly.
Iran has expressed repeatedly that it would immediately return to its commitments based on the JCPOA as soon as the US did so.
About Iran's readiness to send an ambassador to Riyadh, the spokesman expressed hope that talks would reach tangible outcome for establishment of relations.
Asked whether imports of foreign COVID vaccines would be stopped or not, the spokesman said that a cargo was delivered from China last week and the process will continue this week.
At the end, he talked of the nuclear power plant in Bushehr, south of Iran, saying that it is customary for nuclear power plants to go out of the grid a couple of times a year for removing technical problems.
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