United Nations, Sep 25 (IANS): US President Barack Obama and his Iranian counterpart Hassan Rouhani will not meet on the sidelines of the UN General Assembly, said a senior Obama administration official Tuesday.

The official told reporters that Washington is open to having discussion with the Iranians "at any level" but they did not have any plan for a formal bilateral meeting at the presidential level at the United Nations, Xinhua reported.

"We indicated that the two leaders could have had a discussion on the margins if the opportunity presented itself," said the official, noting that it was "too complicated" for Rouhani to have a brief in-person encounter with Obama. Rouhani has traded letters with Obama since taking office in August.

"The Iranians have an internal dynamic that they have to manage, and the relationship with the US is clearly quite different than the relationship that Iran has with other Western nations," said the official.

In his address to the UN General Assembly Tuesday morning, Obama said disputes with Iran over its nuclear programme can't be solved overnight but he sees an opportunity to take a "major step down a long road toward a different relationship".

Obama also said that he has directed US Secretary of State John Kerry to pursue this effort with the Iranian government.

To build on diplomatic opportunities, Kerry would later this week meet with Iranian Foreign Minister Mohammad Javad Zarif and representatives of Britain, France, Germany, Russia and China to discuss the Iran nuclear programme.