International envoy Kofi Annan acknowledged the failure so far of his mission to bring peace to Syria, as more than 60 people were killed in violence that also spilled over into Lebanon.
In comments published by French newspaper Le Monde on Saturday, Annan was quoted as saying that significant efforts had been made to try to resolve the crisis peacefully and politically.
However, the plan had not been successful and perhaps there was no guarantee that it would succeed, he said.
The Annan plan, which insists on a cessation of violence by all sides, has made little headway. Activists say more than 17,000 people have now died since the uprising began in March last year.
UN chief Ban Ki-moon called on Friday for scaling down an observer mission in Syria to refocus on political efforts to end the bloodshed.
Annan, a former UN chief, spoke of the importance of Russia, a Damascus ally which has so far blocked international action against President Bashar al-Assad's regime, while stressing that Iran should be involved in discussions.
The UN-Arab League envoy, whose plan called for a ceasefire that has been ignored on a daily basis since April, said Syria's ally Iran had a role to play in efforts to end the crisis despite US opposition.
On the ground, Syrian forces bombarded towns in the northern province of Aleppo in violence on Saturday that claimed at least 60 lives across the country, the Syrian Observatory for Human Rights said.
"Regime forces are attempting to regain control over this [Aleppo] region, where they suffered heavy casualties over the past months," the Britain-based Observatory said.
"A large number of families have been displaced from the area for fear of shelling and lack of water, electricity and medical services," the watchdog added of the attacks in Aleppo.
In the eastern city of Deir Ezzor, seven members of the same family were among 13 people killed in a bombardment by regime forces, according to the Observatory.
In Damascus, regime forces clashed with rebels and stormed the neighbourhood of Barzeh, attempting to break a strike, while a taxi driver was shot dead in the same area, it said.
The Local Coordination Committees, made up of anti-regime activists in the country, reported general strikes in and around Damascus to honour those killed in the anti-regime uprising.
The latest violence came a day after 93 people were reportedly killed across Syria on Friday, as dozens of protesters took to the streets calling for a "people's liberation war".
In Lebanon, a teenager died when a rocket hit her house in the border region of Wadi Khaled, a Lebanese security official, said, adding that five others were wounded by rockets and exchanges of gunfire.
"A few hours later, an eight-year-old Bedouin girl, who recently fled with her parents from Syria, was killed," said a hospital source in Akkar province.
"A military expert who visited the site said it was either a mine planted in the area or an explosive they were handling," the security source said, after initially reporting that a shell had hit their tent.
A local official said clashes had broken out at dawn between the Syrian army and gunmen on the Lebanese side of the border.
On Friday, some 100 countries and international organisations meeting in Paris urged the Security Council to adopt Annan's peace plan under Chapter VII of the UN Charter.
"We should go back and ask for a resolution in the Security Council that imposes real and immediate consequences for non-compliance, including sanctions," Clinton said.
Clinton urged those present at the meeting to make Russia and China "pay a price" for helping Assad stay in office.
On Saturday, Chinese Foreign Ministry spokesman Liu Weimin shot back: "Any words and deeds that slander China and sow discord between China and other countries will be in vain."
Russia and China say they are committed to the peace plan of Annan that prescribes national dialogue, but reject the position of Western powers and their Gulf Arab allies that Assad must step down to enable reform in Syria.