Washington DC - A senior US official said Sunday the US is ready for "every possibility" amid fears of war between Iran and Israel while telling the Israelis it is "urgent" to reach a ceasefire deal in Gaza.

Following the Pentagon's announcement that it has beefed up the US military presence in the Middle East, White House Deputy National Security Adviser Jon Finer said, "We are preparing for every possibility."

"The Pentagon is moving significant assets to the region, to prepare for what may be another need to defend Israel from an attack, while simultaneously we are working very hard to deescalate this situation diplomatically because we do not believe that a regional war is in anyone's interest in the current moment," he continued, speaking on ABC News.

The US has mobilized more warships and fighter jets to protect its troops and ally Israel from threats by Iran and militant groups backed by Tehran, such as Palestinian Hamas and Lebanese Hezbollah.

Ukraine conflict Zelensky warns Ukraine does not have enough weapons to arm troops

The vows of vengeance followed the Wednesday killing of Hamas leader Ismail Haniyeh in Tehran, hours after the Israeli assassination of Hezbollah's military chief in Beirut.

Israel, accused by Hamas, Iran, and others of carrying out the attack that killed Haniyeh, has not directly commented on it.

Israeli forces meanwhile kept bombarding the Gaza Strip, witnesses and officials in the besieged Hamas-ruled territory said. No end is in sight to the nearly 10-month war triggered by the Palestinian militant group's October 7 attack on southern Israel.

The US, Britain, France, Canada, and Jordan were among the governments calling for their citizens to leave Lebanon.