"Iran launched an unprecedented aerial attack against Israel, and we launched an unprecedented military effort to defend it. Together with our partners, we defended that attack," Biden said as he met Iraq's visiting prime minister.

"The United States is committed to Israel's security. We're committed to a ceasefire that will bring the hostages home and prevent the conflict from spreading beyond what it already has," Biden added in the Oval Office.

Biden was referring to those kidnapped by Hamas militants in their deadly October 7 attack on Israel.

Israel is weighing its response to Iran's massive drone and missile attack on Saturday, which Tehran said was in retaliation for a presumed Israeli strike on an Iranian consulate building in Syria that killed a top general.

Biden has promised "ironclad" support for Israel but also urged it to "think carefully and strategically" before launching a response against Iran that could trigger a wider war.

The US president said he was "also committed to the security of our personnel and partners in the region, including Iraq."

Iraq's Prime Minister Mohamed Shia al-Sudani was visiting the White House for talks on the presence of US troops in Iraq as part of an anti-jihadist coalition.

US Secretary of State Antony Blinken also said Washington did not want any escalation, but would continue to defend key ally Israel.

"We don't seek escalation, but we'll continue to support the defense of Israel and to protect our personnel in the region," Blinken said at the start of a meeting with Iraq's Deputy Prime Minister Mohammed Ali Tamim.

"What this weekend demonstrated is that Israel did not have to and does not have to defend itself alone when it is the victim of an aggression, the victim of an attack," he added, also calling Iran's actions "unprecedented."

Iran launched more than 300 drones and missiles in the attack. Most of those projectiles were intercepted before they reached Israel, with the help of the United States, Jordan and other allies.

Blinken said he was involved in a flurry of talks over the last 36 hours, seeking to coordinate a diplomatic response that would prevent any escalation of the crisis in the region.

The US secretary of state has notably spoken with his counterparts in Egypt, Saudi Arabia, Jordan, Turkey, Britain and Germany, according to the State Department.

The Iraqi deputy prime minister said his government was concerned that the region could be "dragged into a wider war that will threaten international security and safety," calling on all parties to exercise "self-restraint."