Foreign ministers and senior diplomats from 27 nations converged in Myanmar for ASEAN, Asia's highest profile diplomatic meeting this year.
The U.S. has been pressuring China to rein in its assertive actions in the disputed South China sea.
U.S. Secretary of State John Kerry says an American-backed initiative to ease tensions there had made some progress.
(SOUNDBITE) (English) US SECRETARY OF STATE, JOHN KERRY, SAYING:
"I think we made the points that we came to make. We weren't seeking to pass something per se, we were trying to put something on the table that people could embrace."
But China appeared to rebuff U.S. pressure.
Southeast Asian nations also declined to overtly back Washington's proposal for a freeze on provocative acts.
The rancor over the disputed sea has split the 10 members of ASEAN.
Several states are reluctant to take China to task, fearing they could jeopardize their rising trade and investment ties.