Syria has promised to stop fighting in time for the deadline for a cease-fire brokered by special envoy Kofi Annan but reserved the right to respond to any aggression, a significant hedge against any end in the fighting that has convulsed the nation for more than a year.
The statement came as Mr 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 Mr 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 6am Thursday - as the best hope to calm a year-old conflict that has killed 9,000 people.
But the US and others also are sceptical president Bashar Assad's regime will fully comply after several previous failures. Syria disregarded the Tuesday deadline, and was still attacking its opponents with rockets and mortar fire.
In a statement carried on the state-run SANA news agency, a defence 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 official said, adding: "Our armed forces are ready to repulse any aggression carried out by the armed terrorist groups against civilians or troops."
Annan spokesman Ahmad Fawzi said Syrian Foreign Minister Walid Moallem sent a letter with an identical pledge to the joint UN-Arab League envoy. Mr Fawzi said Mr Annan will work with the Syrian government on implementation of his six-point plan to end the bloodshed.
The Syrian uprising is among the most explosive of the Arab Spring, and the UN estimates 9,000 people have been killed in the conflict since March of last year.
In neighbouring Jordan, an interior ministry official said the country was now hosting 95,000 Syrian refugees who had fled the conflict.