There is little chance Iran would risk the international fallout and send large-scale military forces to aid Assad, although it's likely that Iran has boosted its cadre of security advisers and other envoys in Damascus. Instead, Iran seeks to coax Assad to offer some kind of tension-easing dialogue or at least pull back on the attacks.
Any concessions by Assad could open the way for eventual deep reforms in his authoritarian rule. But Iran would gladly take a weakened Assad over the uncertainties under a new Syrian leadership, which would likely put Assad's Iranian-oriented Alawite minority into a political deep freeze.
Does Assad think that giving up some power to remain a tool of Iran is more important than holding on to absolute power no matter what the risk of failure?