Syrian security forces have reportedly killed one person and wounded several others protesting at a mosque in the capital, Damascus.
Activists said "thousands" of people took to the streets in Kafarsouseh, a western suburb, to protest against President Bashar al-Assad's rule after early morning prayers on Saturday.
A witness told Al Jazeera that security forces and shabiha [regime thugs] arrived at the scene, using sound bombs and tear gas in an attempt to stop the demonstration.
Protesters threw rocks and the tear gas canisters back at the security forces, the witness said, and security forces responded with gun fire, injuring eight people.
The witness said protesters were then pushed back into the mosque, which was surrounded by shabiha and security forces.
Activists said security forces stormed the mosque, attacking the 80-year-old imam who was later taken to a Damascus hospital. Parts of the interiors was damaged and about 150 people arrested, according to activists.
While the mosque was besieged, crowds gathered to protest in a square adjacent to the mosque. Activists said five people were injured when security forces opened fire and used teargas to disperse the protesters.
The Local Co-ordination Committees (LCC) said hundreds of people had also protested in the suburb of Moadamiya, and in the Tijara neighbourhood early on Saturday.
Activists called on protesters to converge on the Abaseen Square in central Damascus, but the LCC said only about 60 people had actually arrived at the square.
Later in the day, protesters from Douma, on the outskirts of Damascus, marched towards the centre of the city to protest the mosque attack. When the protesters arrived in the suburb of Saqba, security forces opened fire on them and one person was killed, according to activists.
In the latest call for Assad to pay heed, Iran called on his government to listen to its people.
"The government should answer to the demands of its people, be it Syria, Yemen or other countries," Ali Akbar Salehi, Iran's foreign minister, said on Saturday.
"The people of these nations have legitimate demands and the governments should reply to these demands as soon as possible," the ISNA news agency quoted him as saying.
But Salehi warned against toppling the Syrian government.
A vacuum in the Syria would have an unpredictable impact for the region and its neighbours, Salehi said, referring to calls by the United States and European leaders for Assad to step down.
Meanwhile, Arab foreign ministers meeting in Egypt on Saturday, were to warn Syria they will no longer remain silent on its deadly crackdown on dissent, an Arab diplomat said.
The diplomat, who requested anonymity, said Arab governments agreed ahead of the meeting, scheduled to start at the Arab League's headquarters in Cairo, to pressure Syria for an immediate end to military operations against protesters.
The diplomat said they also agreed to "send a message to the Syrian leader informing him that Arab silence on what is taking place in Syria is no longer acceptable."
In-depth coverage of escalating violence across Syria
Meanwhile, a UN investigative team wrapped up its visit to Syria, concluding that “there is an urgent need to protect civilians” from excessive force, but said it had been unable to fully assess the situation due to government restrictions.
"The constant presence of government officials limited the mission's ability to fully and independently assess the situation," UN spokesman Farhan Haq said.
"The mission concluded that although there's no countrywide humanitarian crisis, there is an urgent need to protect civilians from the excessive use of force."
When the UN delegation arrived in the city of Homs, hundreds gathered in a square, chanting anti-government slogans. Just moments after their convoy pulled out of the city, security forces opened fire on the crowds, and activists said at least three people were killed.
Human rights groups say Assad's forces have killed more than 2,200 people since the uprising against his rule erupted in mid-March, touched off by the wave of revolutions sweeping the Arab world.
The crackdown has led to broad condemnation and sanctions. Assad has ignored international calls for him to step down, insisting that "religious extremists" and "armed terrorist groups" are driving the violence, not "true reform-seekers".
Assad has exploited fears of chaos in Syria, with the regime portraying him as the only man who can guarantee peace in a country with a mix of religious groups.
The opposition, however, says the protest movement is free of sectarian overtones and is simply demanding freedom and democracy.