In a US television interview days before he travels to New York for the UN General Assembly, Rowhani praised US President Barack Obama for taking a "positive" approach toward Tehran in a letter.

"Under no circumstances would we seek any weapons of mass destruction, including nuclear weapons, nor will we ever," Rowhani told NBC News.

"We have never pursued or sought a nuclear bomb, and we are not going to do so," he said, according to the US network.

Rowhani repeated Iran's position that the clerical state -- suffering from US-led sanctions following sensitive uranium work -- was solely "looking for peaceful nuclear technology."

Rowhani, considered more moderate than his rivals, swept to power in June on promises to help repair Iran's economy and to ease tensions with the West.

His stance has been met alternately with cautious optimism and skepticism in Washington, where experts note that supreme leader Ayatollah Ali Khamenei ultimately controls foreign policy.

Rowhani told NBC News: "In its nuclear program, this government enters with full power and has complete authority."

"The problem won't be from our side," he was quoted as saying. "We have sufficient political latitude to solve this problem."

Asked about Rowhani's interview, US Defense Secretary Chuck Hagel said he was "glad" to hear his remarks and that Obama had always been "willing to talk."

"But I think the next step here is let's see how Iran's actions match their words," Hagel told the "PBS Newshour" on public television. (AFP)