The summit begins 24 hours after US, France and Britain launched the air strikes in war-torn Syria.
Arab leaders meet in Saudi Arabia for a summit on Sunday as world powers face off over Syria and tensions rise between Riyadh and Tehran.
Saudi Arabia is pushing for a tough, unified stance against Iran at the annual gathering of the 22-member Arab League.
The summit begins 24 hours after the United States, France and Britain launched the air strikes in war-torn Syria in response to a reported regime chemical attack on the decimated rebel enclave of Eastern Ghouta last week.
Saudi Arabia and Qatar, which both voiced support for the strikes, remain locked in a months-long diplomatic standoff, with Riyadh accusing Doha of supporting extremists and being too close to Iran.
The last time the bloc made a concrete move was in 2011, when it suspended Syria’s membership over the Assad regime’s role in the war.
Syria remains suspended from the organisation.
Custodian of the Two Holy Mosques, King Salman bin Abdulaziz of Saudi Arabia, will chair Sunday’s summit in the eastern city of Dhahran, home to Saudi Arabia’s oil giant Aramco and 160 kilometres (100 miles) across the Gulf from Iran.
Syria’s war, the most complex of the region’s conflicts, is the main point of contention pitting Riyadh and its allies, against regime backer Iran and its Lebanese ally Hezbollah.
Saudi Arabia on Saturday declared its full support for US-led air raids on Syria, which the Pentagon said had “successfully hit every target”.
Gulf Arab states have made massive donations to Syria but have not officially offered asylum to Syrians.
Despite widespread Arab condemnation of the suspected chemical attack, the Dhahran summit is unlikely to call for Assad to step down.
Seven years into a war that has claimed hundreds of thousands of lives, Saudi Arabia and Iran now agree that the country’s future cannot be decided solely by the Assad regime, whose troops have regained the upper hand with massive support from Russia.
The question of Jerusalem is also likely to figure prominently at the summit as the United States prepares to move its embassy there from Tel Aviv after declaring the disputed city the capital of Israel in a break with decades of international diplomacy.
Arab ministers at a preliminary meeting in Riyadh on Thursday focused heavily on blocking the move, unanimously condemning the decision by US President Donald Trump.