Iran's Foreign Minister Ali Akbar Salehi, whose nation is Assad's most staunch regional supporter, told reporters before the opening session in Saudi Arabia that suspending Syria will not resolve the issue of the unrest there.
A wide-ranging tableau of violence and retributions on Wednesday reinforced the U.N.'s warnings.
A blast in central Damascus rattled — but did not injure — U.N. observers, followed by the airstrikes in Azaz. And in tense Lebanon, a powerful Shiite clan that backs Assad said it abducted at least 20 Syrians in retaliation for rebels holding one of their relatives captive in Syria. The rebels accuse the Lebanese man of belonging to Hezbollah, a Shiite Lebanese group allied with Syria and Iran.
The bombing of Azaz brought into stark relief the limits of the rebels' expanding control of Syria's north.
In recent months, rebels have pushed the Syrian army from a number of towns in a swath of territory south of the Turkish border and north of Aleppo, Syria's largest city. About a dozen destroyed tanks and army vehicles are scattered around Azaz, left over from those battles.
As the Assad regime's grip on the ground slips, however, it is increasingly targeting rebel areas with attack helicopters and fighter jets — weapons the rebels can't challenge.
Rebels and residents of the Aleppo countryside say the army rarely hits rebel targets, striking instead at residential areas and killing civilians.
The Azaz bombings appeared to fit that pattern.