Preparatory works have been done for the summit meeting to take place in the Iranian capital, Peskov said, IRNA reported.
He said that planning for participation of Russian President Vladimir Putin in the meeting is underway.
After being finalized through diplomatic channels, the meeting itinerary of the three heads of states will be disclosed, he added.
The three leaders have met twice in Sochi and Istanbul in the framework of Astana Syria Talks.
In the meetings, the three leaders discussed important issues on Syria and ways to help the country to end the crisis.
The third meeting is to be held in Tehran.