Syrian President Bashar al-Assad has seen the region close in around him after a string of neighboring countries have publicly calling for his regime to end its brutal and deadly crackdown on protesters.
Saudi King Abdullah issued a statement as the Syrian army reportedly shelled the eastern city of Deir al-Zour.
He said Syria had to choose between "wisdom" or being "pulled down into the depths of chaos and loss".
"The kingdom of Saudi Arabia... demands an end to the killing machine and bloodshed and calls for acts of wisdom before it is too late," he said.
"Syria should think wisely before it is too late and issue and enact reforms that are not merely promises but actual reforms."
Saudi Arabia, usually reluctant to chastise other Arab countries openly, was the first regional power to take a strong position against the Assad regime.
King Abdullah also announced that his country had recalled its ambassador from Damascus for consultations, a move soon followed by Kuwait and then Bahrain, showing Saudi influence over the region.
Bahrain's Foreign Minister Sheikh Khaled bin Ahmad al-Khalifa called for "a resort to reason," while in Kuwait, Foreign Minister Sheikh Mohammad al-Sabah said the "military option must be halted" and that "no one can accept the bloodshed in Syria" and warned that the Persian Gulf state foreign ministers would meet to discuss the situation further.
Jordan has for now refused to "interfere in Syria's international affairs," but but Prime Minister Nasser Judeh has said the situation was "worrisome, unfortunate and sad."
"We hope that dialogue is restored and reforms are achieved in order to get Syria out of this impasse," he said in a televised statement.
The Arab League issued its first statement on Syria Sunday. It said it was "alarmed" and called for an end to the violence, but the organisation also stopped short of condemning the regime or calling for Assad to step down.
Turkey has also joined in the condemnation of the violence, and Foreign Minister Ahmet Davutoglu is due in Damascus Tuesday with a "tough" message for Mr Assad, he reported.
The grand imam of al-Azhar in Cairo, one of the top clerics in the Sunni Muslim world, also spoke out, saying the situation had "gone too far."
"There is no other solution but to put an end to this Arab and Islamic tragedy," said Grand Imam Sheikh Ahmed al-Tayeb. "The vast repression, the use of the highest levels of violence, arrests and intimidation represent an unacceptable human tragedy."
But Damascus dismissed foreign criticism Sunday and said its critics ignored the fact that the killings were caused by 'armed gangs' and the new reforms the regime has promised.
Presidential adviser Bouthaina Shaaban promised Damascus would not mince words with Davutoglu when he comes visiting Tuesday.
"If ... Davutoglu is coming to Syria to deliver a decisive message, then he will will hear even more decisive words in relation to Turkey's position.
"Turkey still has not condemned the savage murders of civilians and military men by armed terrorist groups," read a statement from Shaaban posted by the state-run SANA news agency.
Shaaban said Syria "always welcomes dialogue with friends, but it has absolutely refused throughout its history attempts to interfere in its internal affairs."
Saudi Arabia, Kuwait and Bahrain have all recalled their ambassadors while Jordan has called for dialogue, but will this be enough to stop Assad, especially when some of those same critics -- the Saudis in particular -- helped Bahrain suppress its own protest movement?
In the spring, Bahrain was shaken by mass demontrations against the al-Khalifa monarchy, which were suppressed with massive force. Saudi Arabia sent in troops and tanks to rescue its fellow Sunni royal family.
Bahrain reportedly also used soldiers imported from countries like Jordan, Pakistan and Yemen.
Observers say Assad seems to be positioning himself for plausible deniability as his forces continue attacking civilians.
A second assault on the city of Deir al-Zour Sunday claimed at least 50 lives, activists said.
Many residents of besieged cities like Deir al-Zour and Hama reportedly are afraid to leave their homes or take the wounded to hospitals for fear of being attacked themselves.
Human rights activists say at least 1,700 civilians have been killed and tens of thousands arrested since the uprising began in mid-March. More than 300 people are believed to have died in the past week alone.
The next few weeks could be decisive for the future of Syria as international and regional pressure on a defiant Assad mounts.