US President Barack Obama and Iranian President Hassan Rouhani had no direct contact at the UN General Assembly in New York despite growing speculation that the two might meet.

However, the 2 countries' foreign ministers will meet on Thursday for the first time in 6 years when they attend multinational talks over Iran's nuclear program.

A high-ranking US official acknowledged on Tuesday that the US tried to arrange an unofficial meeting between Obama and Rouhani. But the official said the Iranian side declined on the grounds that a meeting would be too complicated to set up at this point.

Rouhani told CNN on Tuesday that the 2 sides did not have sufficient time to coordinate the meeting.

The leaders of the US and Iran have not met since the 2 countries severed diplomatic ties more than 30 years ago. The 2 sides are sharply at odds over Iran's nuclear development program.

On the other hand, US Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif will attend talks between Iran and the 5 permanent members of the UN Security Council and Germany. The meeting is aimed at seeking a diplomatic solution to the nuclear issue, and follows the pro-dialogue stance voiced by Rouhani.

All eyes are on whether bilateral ties will have a chance to improve after Kerry and Zarif attend the meeting.

Sep. 25, 2013 - Updated 10:09 UTC