The six-member Gulf Cooperation Council called for an "immediate end to violence... and bloodshed."
Its statement urged a "resort to wisdom and introducing serious and necessary reforms that would protect the rights and dignity of the [Syrian) people, and meet their aspirations."
That call followed a pledge by the US, French and German leaders to consider new steps to punish Syria after a deadly crackdown on the first Friday of Ramadan, the holy Muslim month of fasting.
President Barack Obama spoke separately to France's Nicolas Sarkozy and German Chancellor Angela Merkel as Western nations cranked up pressure on Syrian leader Bashar al-Assad.
"The leaders condemned the Assad regime's continued use of indiscriminate violence against the Syrian people," a White House statement said Friday.
They "also agreed to consider additional steps to pressure the Assad regime and support the Syrian people," it added.
The telephone consultations came as Washington appeared to be moving towards a direct call for Al-Assad to leave.
The Syrian government has sought to crush the democracy movement with brutal force, killing around 1,650 civilians and arresting thousands of dissenters, according to the Syrian Observatory for Human Rights Group.
"Twenty-two people were killed Friday, 15 during daytime protests... and seven at night after the evening Taraweeh prayers," said Abdel Karim Rihawi, who heads the Syrian League for the Defence of Human Rights.
"Among the 15 killed in the daytime, seven were in Irbin, three in Damir and one in Maadamiya," all near Damascus, he said by telephone.
Rihawi added that three others were killed in the central city of Homs and one in Nawa, in the south.
At night, "seven protesters were killed by security forces firing to disperse the demonstrators, two in the Nahri Aisha district of Damascus, four in Homs and one in Douma," an outer suburb of Damascus, he said.
Rami Abdel Rahman, head of the Syrian Observatory, told AFP more than 50 people were seriously wounded.
State news agency SANA, meanwhile, said two members of the security forces were killed and eight wounded in an ambush on a road in the northwestern Idlib region, near the Turkish border.
And gunmen on an apartment block rooftop in Douma shot and wounded two other security force members, it said, while assailants also opened fire in Homs.
Assad's regime blames the unrest on "armed terrorist gangs".
On Friday, communications were completely cut off as the army stepped up an operation to crush dissent in Hama, where security forces killed at least 30 civilians and wounded dozens more earlier in the week.
More than 1,000 families had already fled the central city, according to Abdel Rahman.
"Thousands of demonstrators marched in Deir Ezzor, Daraa and Qamishli in support of the city of Hama despite the extreme heat," said Rihawi, adding they numbered 30,000 in Deir Ezzor alone.
"More than 12,000 people" also marched in Bench, in Idlib province, "to demand the fall of the regime and express their support for Hama and Deir Ezzor," said Abdel Rahman.
The call for Friday's protests came from activists on Facebook group The Syrian Revolution 2011, a driving force behind the demonstrations that have been calling for greater freedoms since mid-March.
Late Friday, scores of Kuwaitis staged two demonstrations in solidarity with Syria's people, demanding the expulsion of the Syrian ambassador and the recall of Kuwait's envoy from Damascus.
The same day in Egypt, several hundred people demonstrated at the Syrian embassy in Cairo under the slogan, "Free Syria, Bashar out."
In Tunisia, several political parties, NGOs and known figures created a collective support group backing Syria's people, said Mokhtar Yahyawi, a former judge and the group's coordinator.
The crackdown on Hama has also prompted harsh words from Washington and Moscow, with Russia hinting at a possible change of heart after stonewalling firm UN action against Syria, its ally since Soviet times.
Washington has already imposed a raft of measures against Assad, his family and associates of the regime, but lawmakers have called on Obama to ban all US businesses from operating in Syria, and for more sanctions.