The White House said Monday there were no current plans for President Barack Obama to see Iran's new president at the UN next week, but did not definitively rule out a meeting.

Obama and President Hassan Rowhani will both be at the annual United Nations General Assembly in New York, ahead of a new round of talks between Tehran and world powers on its nuclear program.

Obama's confirmation in a television interview this weekend that he and Rowhani had exchanged letters has sparked speculation about what would be an eye-opening meeting between the two men.

"There are currently no plans for the president to meet with his Iranian counterpart at UNGA next week," White House spokesman Jay Carney told reporters.

Other officials did not respond specifically, when asked whether they would rule out such a meeting or some kind of engineered informal encounter. They also would not say whether such an approach would be seen in the administration as premature, given uncertainty about Rowhani's intentions on the nuclear dispute.

Carney added that Washington hoped the new Iranian government would be ready to "engage substantively" to ease international concerns about its nuclear program, which the West says is designed to produce weapons.

"We remain ready to engage with the Rowhani government on the basis of mutual respect to achieve a peaceful resolution to the nuclear issue," he said.

A new round of talks between the permanent five members of the UN Security Council plus Germany (the P5-plus-one grouping) and Iran is expected to be convened soon.

Iranian Minister Mohammad Javad Zarif is meanwhile expected to meet EU foreign policy chief Catherine Ashton at the UN.

Carney said that Washington remained willing to "engage in the P-5 plus one or bilaterally" to end the nuclear standoff.

"But we have also been very clear that Iran has flagrantly failed to live up to its obligations under international resolutions and needs to, in a verifiable way, forsake its nuclear weapons program," he said.

Obama told ABC News in an interview that he had reached out by letter to Rowhani, and had also received a letter from the new Iranian president.

Officials declined to say whether Obama or Rowhani initiated the exchange and to detail the content of presidential correspondence.

The United States and Iran have been at loggerheads for decades and have no diplomatic ties. Their antagonistic relations further soured during the presidency of former Iranian leader Mahmoud Ahmadinejad who typically marked UN General Assemblies with inflammatory rhetoric and tirades against the United States and Israel.

Rowhani was elected on a platform of easing the pain inflicted on Iran's economy by US and international sanctions and easing tensions with world powers.

He is seen as more moderate than Ahmadinejad but Washington is still trying to figure out the exact implications of his election.

There are some hopes in the US political and academic community that Rowhani will provide more open to genuine negotiations on the nuclear issue, despite saying earlier this month that Iran would not cede one iota of its nuclear rights.

And as Carney's circumspect remarks indicated, there is skepticism that nuclear policy, which is the province of Iran's Supreme Leader Ayatollah Ali Khamenei, will undergo anything more than a cosmetic change.

Rowhani, one of a group of Iran's original core of revolutionaries, has implied however that Khamenei has given him "flexibility" in the nuclear talks.

Washington's words are also being parsed carefully on Iran policy, in what might be the start of a decisive period in the stop-start negotiations.

Obama has warned that he is willing to use military force to halt Iran's nuclear ambitions if diplomacy fails and told ABC his reluctance to use force in Syria should not be taken in Tehran as a harbinger of his stance on Iran.

But he also said that Iran should see a "lesson" from the Syrian chemical weapons standoff that intractable disputes can be resolved diplomatically.

Iran denies that its nuclear program is geared towards producing atomic weapons.