Iranian President Hassan Rouhani addresses the UN General Assembly on Tuesday.|Brendan Mcdermid/Reuters

The Iranian president's first speech to world leaders was absent of anti-Israel rhetoric and offered negotiations with the United States and its allies over the disputed nuclear program, showing a more moderate face of Teheran.

However, Iranian President Hassan Rouhani also took repeated digs at the US and the West on Tuesday, much like those that were staples of his predecessor's annual messages to the United Nations General Assembly.

Rouhani's speech signaled Iran's return to a more measured, if still resolute, approach in its foreign policy even as it delivered a reality check that diplomatic warming will not come quickly or easily.

Karim Sadjadpour, an Iran expert at the Carnegie Endowment for International Peace in Washington, said he did not think Rouhani's speech was conciliatory. But his predecessor Mahmoud Ahmadinejad "set an incredibly low bar for dignified behavior" and Rouhani delivered a less polarizing, less divisive speech, he said.

"Given how vitriolic that Ahmadinejad's language was, in contrast he certainly appears as a moderate," Sadjadpour said.

Rouhani even went a step further in an interview with CNN that aired on Wednesday, saying "the crime the Nazis created toward the Jews is reprehensible and condemnable".

Ahmadinejad, in contrast, once called the Holocaust a "myth" and later said more research was needed to determine whether it had really happened.

And while Rouhani briefly touched on what he described as Palestine's depravation and subjugation, he also ended his speech with a reference not only to the Quran and Bible, but also the Torah.

Earlier on Tuesday, Rouhani said the ice was already "beginning to break" between his country and the West, although no meeting or handshaking has taken place with his US counterpart, Barack Obama, in New York.

There had been reports and speculation that Obama and Rouhani might meet informally on the sidelines of the UN General Assembly session. But White House officials confirmed on Tuesday that no such bilateral meeting would take place. They indicated that such an encounter would prove "too complicated" for the Iranian side back home.

"Relations between Iran and the US have been very tense over the past few years. US sanctions on Iran greatly affected the country's economy and restricted its connections with other states," said Hua Liming, former ambassador to Iran, United Arab Emirates and the Netherlands.

Despite his moderate manner, Rouhani's speech also shows that Iran will not give up its right to peacefully use nuclear resources, Hua added.

The Iranian-US relationship still has a long way to go, with Israel being the biggest obstacle. Obama is willing to improve bilateral relations because Iran is the key factor in many regional issues in the Middle East. Israel, on the other hand, sees Iran as a major threat out of geopolitical considerations.

"China will also benefit from an improved Iranian-US relationship," Hua said.

When asked about his expected meeting with Obama, Rouhani said there had been "some talks" to arrange a meeting to give the two an opportunity to "talk with each other" but there was not sufficient time to really coordinate such a meeting.

"But speaking of the icebreaking you mentioned, it's already beginning to break because the environment is changing. And that has come about as a result of the will of the people of Iran to create a new era of relations between Iran and the rest of the world," Rouhani said in Persian.

Asked whether he was "authorized" by the Iranian supreme leader to make his recent moves to improve ties with the West, Rouhani said the Iranian president has the authority to talk with others when national interests dictate.

Xinhua-China Daily-AP