Israel-Gaza updates: 22, including 18 children, reported dead in Rafah strikes

Israeli aviation authorities say they are closing the country's airspace to all flights at 12:30 a.m. local time, 5:30 p.m. ET.

Flights would be affected and advised travelers to check with their airlines for changes.

Iranian state television also announced that Tehran had launched an attack toward Israel. Iraq's state news agency quoted Transportation Minister Raqqa Saadawi as saying the country's airspace was closed.

Before the attack was announced, a FlyDubai flight from Dubai in the United Arab Emirates to Tel Aviv, Israel, turned around as it was over Saudi Arabia, flight-tracking data showed. United Airlines also canceled a Saturday flight from Newark to Tel Aviv and the return flight.

Iran's Islamic Revolutionary Guard Corps announced that it has launched extensive missile and drone operations against targets in Israel, according to Tasnim, the Iranian news-agency affiliated with the branch of Iran's armed forces.

An Israeli source also confirmed to ABC News that Iran fired cruise missiles from Iraq as well.

In a post on X, the Iranian Foreign Minister said "necessary warning has been given to America."

The U.S. will try to help Israel intercept everything possible -- not just those that pass over U.S. ships -- despite Iran informing the U.S. that they should stay out of it, a senior U.S. official confirmed to ABC News.

In the coming hours the U.S. expects missile launches from Iran and southern Lebanon -- and maybe even the Houthis -- as well as drones, which take longer to reach target. The Iranians are trying to overwhelm the Israeli air defenses with drones and missiles coming in at different altitudes, speeds and directions -- but hitting targets at the same time, according to the official.

While the U.S. expects that most of these will be intercepted -- upwards of 85% -- the fear is that if any Israeli lives are lost, the Israeli response will be much bigger.

The target is believed to be three military bases, especially one where F-35s are kept. While these bases are relatively remote, there are towns nearby and these Iranian weapons are not completely accurate.

The U.S. has no doubt Israel will respond whether lives are lost or not. And that Iran itself will be targeted.

-ABC News' Martha Raddatz

Sources at the White House say there’s deep concern that an Iranian retaliatory strike against Israel -- and the possible Israeli response -- will widen this war.

President Joe Biden cut his weekend vacation short to consult with his national security team in preparation for this. They’ve been on high alert and knew this attack was imminent.

U.S. officials the military is prepared to provide assistance to defend Israel against attacks if needed.

The U.S. is already moving military assets to the region to deter Iran and help protect U.S. forces. Officials say they have been urging Iran against further escalation or attacks on U.S. forces. They’ve been stressing that the U.S. was not involved in the Damascus, Syria, strike earlier this month.

-ABC News' Selina Wang