NEW YORK — U.S. and Iranian officials emerged from high-level talks on Iran’s nuclear program Thursday pleased with the positive tone of the negotiations – but noted that a lot of work lies ahead to resolve a standoff with Tehran.
Diplomats from the U.S., China, Russia, Britain, France and Germany met with Iranian Foreign Minister Mohammad Javad Zarif on the sidelines of the U.N. General Assembly in New York. Secretary of State John Kerry had an additional one-on-one meeting with Zarif following the talks, saying he welcomed the change in tone.
"Needless to say, one meeting and a change in tone, which was welcome, doesn't answer those questions yet and there is a lot of work to be done," Kerry said.
He later added, "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."
Zarif, who described the talks as “substantive,” echoed these feelings.
“I’m satisfied with this first step, now we have to see whether we can match our positive words with serious deeds,” Zarif said, adding that his country hopes to achieve a complete lifting of international sanctions imposed on Iran over its nuclear activities.
British Foreign Secretary William Hague described the talks as “extremely good.”
Earlier Thursday, Kerry, asked how Iran can show it is serious about resolving the dispute over its nuclear ambitions, told reporters: “I will let you know after they have been serious.”
The secretary made the remark during an appearance with the Chinese foreign minister, part of a series of photo opportunities with fellow diplomats and world leaders at the United Nations General Assembly.
Kerry also joked, during an appearance with the prime minister of Pakistan, that the one-on-one meetings are “speed-dating diplomacy.”
The remark on Iran came hours before Kerry and his counterparts from five other countries were to meet with the top diplomat in Iran to talk about its nuclear program, a centerpiece of discussion at the General Assembly.
Earlier this week, President Barack Obama told the General Assembly that the United States and Iran could start down a “long road towards a different relationship — one based on mutual interest and respect.”
He directed Kerry to work with European allies, Russia and China to pursue an agreement with the government of Iran, which insists that its nuclear ambitions are peaceful.
Hassan Rouhani, the newly elected president of Iran, told the assembly on Tuesday that his country poses “absolutely no threat to the world” and that he is engaged in talks to resolve the dispute over Iran’s nuclear program.
And on Thursday, Rouhani called for the eradication of nuclear arms from the world because “there are no right hands for these wrong weapons.”
He invoked the bombings of Hiroshima and Nagasaki and said that any use of a nuclear weapon is a “crime against humanity.” He said that the world should focus instead on wiping out poverty, ignorance and disease.
“Let us bestow upon future generations a nuclear weapon-free world,” he said. “This is their right and our responsibility. Let us prove that we are the United Nations, nations united for peace.”
Rouhani made the remarks at a General Assembly session on nuclear disarmament. He also took to Twitter to express the sentiment.
Rouhani has made headlines all week at the General Assembly. On Tuesday, he skipped a luncheon at which some diplomatic observers thought he might shake the hand of President Barack Obama — what would have been a historic gesture.
And on Wednesday, Rouhani repudiated his predecessor’s denial of the Holocaust, although he hedged. He said the Nazis “carried out a massacre that cannot be denied, especially against the Jewish people,” but that it was for historians to decide the scale.
NBC News' Becky Bratu contributed to this report.