He made his remarks after holding talks in Moscow with his Turkish counterpart Mevlut Cavusoglu and, later, Iran's Mohammad Javad Zarif.
"This process was formed on this simple concept that Syrian crisis will exclusively be solved politically in the framework of a real comprehensive procedure led and authorized by the Syrian people themselves and with full respect to territorial integrity, sovereignty and independence of Syria", asserted the top Iranian diplomat.
"Today, the U.S. supports terrorist organisations, and this has to stop", Cavusoglu said.
Under the agreement, nuclear-related sanctions put in place against Iran were lifted in exchange for curbs on Tehran's nuclear program.
The US president is a stern critic of the nuclear deal, reached between Iran and the five permanent members of the UN Security Council - the United States, France, Britain, China, Russia - plus Germany.
The Turkish foreign ministry said Saturday's meeting "will focus on all aspects" of cooperation and "elaborate on the steps that could be taken from now on", while the Russian foreign ministry said talks would focus on the humanitarian situation. American statements about supporting the territorial integrity of Syria "are only words that, apparently, cover plans for reformatting the Middle East and plans for dividing Syria into parts", Lavrov said.
Lavrov said they "set back efforts to promote the political process" and Zarif criticized Washington's "destructive role".
Today, Sergei Lavrov held a special meeting in Moscow with their allies to review potential peace talks.
Lavrov said the US-led missile strikes on Syria "seriously aggravated the situation".
At the meeting, all three ministers agreed Syria must remain a sovereign and whole entity.
The Iranian diplomatic chief urged the worldwide community to take the issue of humanitarian concerns as the top priority in considering Syrian crisis.