Current and former U.S. officials expressed fears on Tuesday that Israel’s airstrikes on an Iranian embassy compound in Syria could escalate hostilities in the region, and prompt retaliatory strikes against Israel and its American ally.

The officials said the attack, which killed three generals in Iran’s Quds Force and four other officers on Monday, had dealt a serious blow to the force, the external military and intelligence service of the Islamic Revolutionary Guards Corps.

Ralph Goff, a former senior C.I.A. official who served in the Middle East, called Israel’s strike “incredibly reckless.”

“It will only result in escalation by Iran and its proxies, which is very dangerous” to American troops in the region who could be targeted in retaliatory strikes by Tehran’s proxies, Mr. Goff said.

Indeed, after the Israeli strike, in Damascus, Syria’s capital, American troops based in southeastern Syria knocked down an attack drone, a Defense Department official said. It was unclear if the drone was aimed at the U.S. forces, the official said, speaking on the condition of anonymity to discuss operational details. If it were, it would be the first attack by Iran-backed militias against American troops in Iraq or Syria in nearly two months. No injuries or damage were reported.

The official said there had been no further attacks overnight, but that Pentagon officials were monitoring the situation closely.