The United States is on high alert and preparing for a possible attack by Iran targeting Israeli or American assets in the region in response to Israel's strike on the Iranian embassy in Syria, a U.S. official said on Friday.

"We're definitely at a high state of vigilance," the official said in confirming a CNN report that said an attack could come in the next week.

Suspected Israeli warplanes bombed Iran's embassy in Damascus on Monday in a strike that killed an Iranian military commander and marked a major escalation in Israel's war with its regional adversaries.