The statement came Wednesday as Annan was in Tehran to seek support for his faltering plan to stop the country's slide toward civil war. Iran is one of Syria's most powerful allies.

Many world leaders see Annan's plan — which called for Syria to pull its tanks back to barracks on Tuesday, followed by a full cease-fire by both sides by 6 a.m. Thursday — as the best hope to calm a year-old conflict that has killed 9,000 people.

But the U.S. and others also are skeptical President Bashar Assad's regime will fully comply after several previous failures. Syria disregarded the Tuesday deadline, and was still attacking its opponents Wednesday with rockets and mortar fire.

In a statement carried on the state-run SANA news agency, a defense official said Syria's army successfully fought off "armed terrorist groups," which is the term Damascus uses to describe those behind the country's year-old uprising.

"A decision has been taken to stop these missions as of the morning of Thursday, April 12, 2012," the unnamed official said, adding: "Our armed forces are ready to repulse any aggression carried out by the armed terrorist groups against civilians or troops."