The Arab League has sent what it calls an urgent message to the Syrian government, denouncing the continued killings of civilians taking part in protests.
The league's ministerial committee on the Syrian crisis also urged Damascus to "take the necessary measures" to protect civilians.
The call came as at least 37 protesters were killed in Syria, activists say. They say the deaths took place mostly in Homs and Hama as protesters called for a no-fly-zone to be imposed, the BBC reports.
More than 3000 people have died in the unrest since protests broke out in March.
The government of President Bashar al-Assad says the unrest is being stoked by armed gangs and foreign extremists looking to stir up sectarian strife.
The Arab League committee says it will meet Syrian officials on Sunday in Qatar to try to reach "serious results" on a way to end the crisis.
The ministers also say they held "frank and friendly" talks with Mr Assad on Wednesday.
Protesters call for NATO protection
Earlier on Friday local time, protesters in Syria called for international protection from NATO, whose warplanes played a vital role in the overthrow of Libyan leader Muammar Gaddafi.
"God, Syria, we want a no-fly zone over it," protesters shouted in the Bab Tadmur neighbourhood of Homs, while others carried banners demanding international protection, according to a Reuter report cited by the BBC.
Agence France-Presse, quoting the London-based Syrian Observatory for Human Rights, reports that an armed insurgency has emerged over the past few weeks around Homs, which is home to one million people.