The Syrian government was expected Thursday to announce its decision on a temporary ceasefire proposed by international peace envoy Lakhdar Brahimi.
The rebel Free Syrian Army said it would adhere to the truce, which would take place over the four-day Muslim festival of Eid al-Adha that starts on Friday, but only if President Bashar al-Assad's troops did so as well.
"We will observe it as long as the regime does," said Colonel Kassim Saad Eddine, the FSA spokesman.
However, an Islamist militant Syrian opposition group, called the al-Nusra Front, has already rejected Brahimi's proposal.
In the latest developments on the ground, al-Assad's troops shelled pro-rebel areas in the outskirts of Damascus, reported the opposition Syrian Observatory for Human Rights.
At least 220 people were killed in Wednesday's violence, according to the London-based organization.