The army has been shelling rebel positions in the largest city, Aleppo. There was also bloodshed in Hama and the capital, Damascus.
The aim of the UN resolution is to pressure the Security Council to act.
Correspondents say this is a clear recognition that the political process has failed.
Fighting is continuing in Aleppo, where government forces have been trying to reclaim areas seized by the Free Syrian Army (FSA) in the past two weeks.
On Friday, the FSA said it had taken 50 per cent of the city. The claim could not be independently verified.
UN peacekeeping chief Herve Ladsous told the Security Council that UN observers in Aleppo were seeing “a considerable build-up of military means, where we have reason to believe that the main battle is about to start”.
Activists say 170 people died across the country on Thursday - including dozens in Hama, to the south of Aleppo.
At least 15 people were reported killed when mortars hit a Palestinian refugee camp at Yarmouk, on the southern edge of the capital, Damascus, late on Thursday. Both sides blamed one another for the incident.
The shelling spilled over from neighbouring areas where government troops have been battling to dislodge rebels.
Activists say more than 20,000 people - mostly unarmed civilians - have died in 17 months of unrest.
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