UN and Arab League envoy to Syria, Kofi Annan, has said he has held "very candid and constructive" talks with President Bashar al-Assad in Damascus.
He told reporters they had "agreed an approach" to end the violence, and he would share this with rebel groups.
Mr Annan admitted on Saturday that the international community's efforts to find a political solution to the escalating violence had not succeeded.
A ceasefire was supposed to begin in mid-April as part of his peace plan.
Opposition activists said security forces were shelling parts of the cities of Deir al-Zour, Deraa, Homs, Aleppo and Damascus on Monday.
More than 100 people were killed on Sunday, mostly civilians, they added.