Shells rained down on several neighbourhoods of Homs Friday, monitors said, a main rebel bastion which has been the focus of much of the Assad regime's year-long crackdown on anti-regime protests, said the Syrian Observatory for Human Rights.
Two people were killed near Bsas village, in Homs province, when the car in which they were travelling was fired upon, said the Britain-based monitoring group.
Before dawn, fighting broke out between the armed forces and rebel fighters in the towns of Harasta and Irbin, in Damascus province, after insurgents fired rocket-propelled grenades at a security post.
Fierce fighting was also reported in the provinces of Hama, in central Syria, and Deir Ezzor in the east, said the Local Coordination Committees, which organises anti-regime protests.
Internet-based activist group The Syrian Revolution 2011, one of the main motors of the uprising, called for people to take to the streets after the weekly Muslim prayers on Friday to protest against the Arab world's inaction.
"The Muslims and the Arabs have abandoned us... but God is with us... and our determination will carry us to victory," the group said in a statement posted on its Facebook page.
An Arab League summit in Baghdad on Thursday, largely ignored by Sunni Arab states, approved a resolution calling for an end to the Syrian regime's crackdown on dissent, for the opposition to unite and for parties to the conflict to launch a "serious national dialogue."
The opposition had urged a harsher statement backing hardliners Qatar and Saudi Arabia, who have called for Assad to step down and for rebels opposing his regime to be supplied with arms.
Iraqi Prime Minister Nuri al-Maliki however steered the summit away from this option, saying that giving weapons to either side "will lead to a regional and international proxy war in Syria."
In response, Syrian activists blocked a street and burned tyres late Thursday in the Al-Aassali neighbourhood of Damascus to protest the "failure of the Arab League," according to a video posted on the Internet.
Assad said he accepts a peace plan drawn up by Kofi Annan, stressing the UN-Arab League envoy's plan would succeed only if "terrorist acts" backed by foreign powers stopped across the country, SANA reported.
The United States was unimpressed with his comments.
The international envoy for Syria, Kofi Annan, expects Assad to implement his peace plan immediately, the former UN chief's spokesman said Friday.
"We expect him to implement this plan immediately. Clearly we have not seen a cessation of hostilities on the ground. This is our great concern," the spokesman said, adding that the "deadline is now" for the Syrian regime to cease all violence.
"We've seen absolutely nothing on the ground that indicates that they're adhering to its calls for Syrian artillery and heavy weaponry to go back to barracks and for a ceasefire," said State Department spokesman Mark Toner.
"We want to see an end to the violence as soon as possible so that we can get humanitarian assistance in to the beleaguered Syrian people," he added.
US Secretary of State Hillary Clinton arrived Friday in Saudi Arabia where she is scheduled to hold talks with Saudi King Abdullah in a bid to crank up pressure on Assad to end the crackdown.
The United Nations estimates more than 9,000 people have been killed in the campaign to crush the anti-regime movement that erupted with democracy protests in March last year.
On the ground, monitors reported that 36 people were killed in violence across the country on Thursday, while the UN said at least one million Syrians were in dire need of need humanitarian assistance.
After her trip to Saudi Arabia, Clinton is due to travel to the Turkish city of Istanbul for a meeting of the "Friends of Syria" group on Sunday.
At the gathering, representatives of 71 countries are expected to come up with measures to ward off a Damascus backtrack on Kofi Annan's peace initiative.
"The main objective of this conference is to increase the pressure on the Syrian regime to end the bloody repression," a Turkish official said.
Turkey, Syria's northern neighbour, has been a vocal critic of Assad's deadly crackdown.
Prime minister Recep Tayyip Erdogan said on a visit to Tehran that Syria should heed the will of its people by implementing political reforms and allowing free elections.
"The Syrian regime should be receptive to the will of its people, who want elections and democracy," the Turkish leader said, according to an interview aired on Iranian state television late Thursday.
"If (President) Bashar al-Assad is not afraid, and is confident about his regime, he should allow the formation of new (political) parties," Erdogan said.
Assad's Baath party controls political life in Syria, which many fear is on the verge of civil war.