As with recent comments by Russian officials, Yang's remarks were more pointed and direct than in the past, an indication that Beijing is looking for progress toward a reduction of violence that might dilute some of the criticism Beijing has come under for blocking U.N. action on Syria.
Separately, Foreign Ministry spokesman Liu Weimin said Vice Premier Li Keqiang would visit Russia later this month, with Syria likely to be on the agenda.
The U.N. insists the fragile truce is holding, even though regime forces have been hammering Homs with artillery for days.
China has sent envoys to meet with various parties in the conflict and says it plans to host opposition figures soon.
Despite the continuing violence, the plan put forward by Annan, the joint U.N.-Arab League emissary, is the only one a deadlocked international community could rally behind and is seen as the only practical way forward. China and Syria's other allies back the initiative because, unlike an Arab League plan earlier this year, it does not require Assad to step down ahead of transition talks.
China, sensitive to anti-government unrest in minority areas in Xinjiang and Tibet, is habitually opposed to such outside intervention.
Associated Press writer David Wivell contributed to this report.