Kerry & Zarif
U.S. Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif are seated during a meeting at United Nations headquarters in New York Sept. 26, 2013. Reuters

Shifting gears in the discussion between the United States and Iran over Tehran’s nuclear program, Secretary of State John Kerry and Iran’s Foreign Minister Mohammad Javad Zarif held talks on Thursday, on the sidelines of a United Nations summit in New York.

The meeting, which is reported to be the highest-level diplomatic interaction between the two nations since 1980, happened on the sidelines of Iranian President Hassan Rouhani's visit to New York for the annual meeting of the U.N. General Assembly. Rouhani has generated considerable buzz with his conciliatory stance accompanied by calls to make amends with the U.S. and its Western allies -- an approach that is in stark contrast to the antagonistic foreign policy stance of his predecessor Mahmoud Ahmadinejad.

A high-level meeting that ended a breakdown in negotiations was scheduled on Thursday between Iran and P5+1 nations, including U.S., UK, France, Russia, China and Germany, but Kerry, who was seated next to Zarif, reportedly invited the Iranian minister for an informal private chat after the scheduled meet, news reports said.

“We had a constructive meeting, and I think all of us were pleased that Foreign Minister Zarif came and made a presentation to us, which was very different in tone and very different in the vision that he held out with respect to possibilities of the future,” Kerry was quoted as saying by NBC News after the talks, which were held without Kerry’s or Zarif’s aides.

“Needless to say, one meeting and a change in tone, which was welcome … there is a lot of work to be done,” Kerry said.

The meeting is the first one involving high-profile leaders since both nations severed all diplomatic relations after the Islamic Revolution of 1979, which saw the rise of Ayatollah Ruhollah Khomeini, and the ouster of pro-Western leader Shah Mohammad Reza Pahlavi.

Zarif said the talks were “substantive,” adding: “I’m satisfied with this first step, now we have to see whether we can match our positive words with serious deeds.”

Talks to strike a nuclear deal will resume on Oct. 15 in Geneva, Reuters reported, after Rouhani called for a deal within three to six months, saying Iran was prepared to accommodate extensive transparency measures to gain the trust of Western nations.

Rouhani also called for a global eradication of nuclear weapons in his address to the General Assembly, saying any use of nuclear weapons anywhere in the world is a “crime against humanity.”

“No nations should possess nuclear weapons as there are no right hands for these wrong weapons,” his Twitter account stated, reiterating his remarks to the UN assembly.