In talks in Saint Petersburg with Russian President Vladimir Putin, EU President Herman Van Rompuy said the EU and Russia "might have some divergent assessments" of the situation in Syria.
But he said they agreed that implementing the troubled peace plan brokered by UN-Arab League envoy Kofi Annan was the only way forward in a situation that risks developing into full-scale civil war.
Government forces attacked rebel strongholds in Idlib province in the northwest and Deir Ezzor in the northeast as violence nationwide claimed nine lives today, the Syrian Observatory for Human Rights said.
The Britain-based watchdog said that the fighting in Idlib's Jabal al-Zawiya hill district, in which two rebel fighters were killed, was the most intense since the uprising against President Bashar al-Assad's regime erupted in March last year.
In Deir Ezzor, the government deployed helicopters to strafe suspected rebel hideouts in farmland in the Sbeikhan district and one was hit by rebel fire, the Observatory said.
The fighting came a day after Assad vowed to crush the rebel Free Syrian Army (FSA), which announced on Friday that it was resuming "defensive operations" because of the failure of a UN-backed ceasefire that was supposed to go into effect from April 12.
The Syrian Observatory said 19 soldiers, eight rebels and 19 civilians were killed in violence across the country yesterday. On Saturday, 57 soldiers were killed nationwide, the biggest single day losses for the military of the uprising, the watchdog said.