The U.S. is reviewing its military deployment in the Middle East amid the threat of Iran's retaliation against Israel's attack on its diplomatic mission in Syria, a top security official said Friday.

Iran's threats toward Israel have increased following an airstrike on the Iranian embassy compound in Syria on April 1 which killed several military generals, including Brigadier General Mohammad Reza Zahedi, who was a senior leader in Iran's elite Quds Force.

The U.S. embassy in Israel also issued a security warning for its employees in light of the threats.

It would be "imprudent and irresponsible if we weren't also taking a look at our own force posture," National Security Council spokesman John Kirby said in Washington on Friday. It was a matter of protecting U.S. personnel and facilities in the region, he said.

"We still deem the potential threat by Iran here to be real, to be viable, certainly credible, and we're watching it as closely as we can," he told reporters.

Kirby did not comment on reports that an attack was imminent. "I've seen reporting out there and I can't speak to what the intelligence picture tells us about the size of what that attack might look like," he said.

U.S. broadcaster CBS reported on Friday that a retaliatory strike could involve more than a hundred drones and dozens of missiles capable of hitting military targets inside Israel.

Kirby said that the U.S. was doing everything it could to ensure that Israel had what it needed to defend itself.

Iran's Supreme Leader Ayatollah Ali Khamenei had said that the airstrike, which Israel which Israel has not claimed responsibility for, was just like an attack on Iranian territory.

In Berlin, German Chancellor Olaf Scholz expressed concern about a possible imminent retaliatory attack. The situation is being taken "very seriously," Scholz said on Friday.

Both he and Foreign Minister Annalena Baerbock had done everything possible to make it clear to Iran "that there must be no military activity here."

U.S. State Department spokesperson Matthew Miller said Secretary of State Anthony Blinken called counterparts including the Turkish, Chinese and Saudi foreign ministers "to make clear that escalation is not in anyone's interest and that countries should urge Iran not to escalate."

Iran is the third-largest oil producer in the Organization of the Petroleum Exporting Countries (OPEC) group, and oil prices stayed near six-month highs on Thursday.