The Syrian army said Wednesday it was observing a 72-hour ceasefire across the country for the holidays marking the end of the Islamic holy month of Ramadan.
The announcement did not say if the truce extends to jihadists of the Islamic State (ISIS) group or Al-Qaeda-affiliated Al-Nusra Front, but a security source said they were apparently excluded.
Previous ceasefires have excluded the two groups and, in fact, Al-Nusra has in the past called to intensify the attacks against the Syrian regime during the ceasefire.
As fighting continued on the ground, especially in second city Aleppo, some rebel groups said they would respect the truce although they doubted the seriousness of President Bashar Al-Assad's regime.
Syria's conflict began in 2011 with the brutal repression of anti-government demonstrations and has evolved into a complex multi-front war.
Attempts to implement ceasefires in Syria have repeatedly failed, as have diplomatic efforts to end a five-year civil war that has killed more than 280,000 people and forced millions from their homes.
The latest takes effect during the three-day Eid al-Fitr festival marking the end of Ramadan, when devout Muslims fast from dawn until dusk.
"A 'regime of silence' is applied across all territory of the Syrian Arab Republic for 72 hours from 1:00 am on July 6 to midnight on July 8," the army said as it announced the move.
Earlier on Wednesday, Assad attended Eid prayers in third city Homs, in a rare public appearance outside the capital.
State television showed him joining worshippers at the Al-Safa mosque in Homs, which is mainly under government control except for a besieged neighborhood on the city's outskirts.
Meanwhile in Tbilisi, U.S. Secretary of State John Kerry welcomed the "Syrian army's declaration of a period of quiet in honor and celebration of Eid".
"So is 72 hours enough? The answer is simple: 'no'. Is 72 hours more welcome than nothing? The answer is 'yes'," he added.
A ceasefire announced by Russia and the United States in late February has mostly collapsed amid repeated violations.
Temporary truces have also been announced in recent months for Aleppo, scene of some of the heaviest fighting in the war, but have fallen apart.
Aleppo, Syria's pre-war commercial hub, is divided between a rebel-held east and regime-controlled west.
Eastern districts have faced heavy bombardment including regime air strikes, while rebels regularly fire rockets into the west.
AFP contributed to this report.