International mediator Lakhdar Brahimi has met Syria's Foreign Minister Walid al-Moualem in Damascus.
Mr Brahimi called for a ceasefire during next week's Islamic Eid al-Adha to stem the bloodshed in the 19-month-old conflict.
There were no immediate details on the talks but Syria has so far given a guarded response to his proposal, suggesting it wants guarantees that rebels would reciprocate any move by President Bashar al-Assad's forces.
Mr Brahimi, the joint UN-Arab League special envoy for the Syria crisis, has been criss-crossing the region with the aim of convincing Mr Assad's main backers and his foes to support the idea of a truce during the holiday, which starts at dusk on Thursday.
Turkish Foreign Minister Ahmet Davutoglu has called for all sides to observe the three- or four-day ceasefire.
Iran, one of Mr Assad's major backers, has also supported the call but added that the main problem in Syria was foreign interference.
The United States, which has been a vocal critic of Mr Assad but has little apparent influence on the ground, also threw its weight behind the ceasefire call.
"We urge the Syrian government to stop all military operations and call on opposition forces to follow suit," State Department spokeswoman Victoria Nuland said.
A previous ceasefire in April collapsed after just a few days, with each side blaming the other. Mediator Kofi Annan resigned his post in frustration a few months later.
The violence has spread across Syria's frontiers.
President Assad's forces exchanged cross-border artillery fire with Turkey several times this month and yesterday a huge car bomb in Beirut killed a top intelligence official whose investigations had implicated Syria in trying to stoke violence on Lebanese soil.
Next week's truce, if it goes ahead, would be self-imposed, with no international observers, and there has been no sign of a reduction in violence ahead of the Eid.
The Syrian Observatory for Human Rights has reported heavy clashes on the main north-south highway connecting Damascus with Aleppo.
The highway town of Maarat al-Numan and villages around it in Idlib were shelled, as part of a several-day campaign after rebels took it a week ago.