Eastern Ghouta, an opposition-controlled suburb of Damascus, is the anti-Assad forces’ last bastion in the capital.
The prime minister has indicated he has no plans to step aside, even as Israel’s attorney general weighs an indictment.
The Israeli prime minister is accused in two cases involving alleged bribery and political favors.
Moscow has been playing down the incident amid concerns about the potential for a broader war.
Images of the unmanned craft released by Israel’s military resemble a U.S. stealth drone captured by Iran in 2011.
The operation, the largest in years, comes a month before a presidential election.
The overnight clash came after pro-government forces attacked a U.S.-backed base, prompting the Americans to retaliate in “self defense.”
The raids hit hospitals and residential buildings and were in apparent retaliation for the rebel downing of a Russian jet.
The public rallies around the operation, stirring nationalist sentiment and giving a boost to Erdogan.
Moscow says “precision weapons” killed 30 militants in northern Syria, where a surface-to-air missile brought down the jet Saturday.
The crackdown netted 381 people, of whom 56 remained in custody, the Saudi attorney general said.
The conference in Sochi ended with limited achievements amid the boycott.
Opposition activists dismiss the move as a ruse meant to give the impression of a fair contest.
Israelis warmly welcomed the vice president; Palestinians snubbed him.
Erdogan's remarks came as Turkish forces clashed with Kurdish fighters in northern Syria for the third day.