President Joe Biden told reporters Friday afternoon he expects an Iranian strike on Israel to occur "sooner than later" amid urgent concerns that Iran was about to retaliate for the bombing of its consulate in Damascus, Syria, earlier this month.

Asked for his message to Iran in the tense moment, Biden was blunt, saying simply, "Don't."

"Would the U.S. respond?" ABC News Chief White House Correspondent Mary Bruce asked repeatedly as the president walked away after the end of an unrelated event. He paused, thought for a moment and then returned to the lectern.

"We are devoted to the defense of Israel. We will support Israel. We will help defend Israel and Iran will not succeed," he said.