The United States does not want to see an escalation of the crisis in the Middle East, a top White House official said Sunday after Israel repelled a massive missile and drone attack from Iran.

"We don't want to see this escalate," White House National Security Council spokesman John Kirby said on NBC's "Meet the Press". "We're not looking for a wider war with Iran."

Israel was on high alert Sunday after Iran's unprecedented attack sparked fears of a broader conflict.

Iran launched its first-ever direct assault on Israeli territory late Saturday in retaliation for a deadly strike by Israeli on Tehran's consulate in Damascus on 1 April.

Iran's retaliation marked a major escalation of the long-running covert war between the regional foes.

US President Joe Biden has reaffirmed Washington's "ironclad" support for Israel, while appearing to guide its staunch ally away from a military response.

News outlet Axios said the president had told Netanyahu he would oppose an Israeli counterattack against Iran and that the prime minister should "take the win".

Kirby added in the interview that the United States is "staying vigilant" to any Iranian threats to American troops. 

"We made it very clear to all parties, including Iran, what we would do ... and also how seriously we would take any potential threats to our personnel," Kirby said.

Iran launched more than 300 drones and missiles towards Israel late Saturday, injuring 12 people, the Israeli army said.

But almost all were intercepted before they reached Israeli territory, the army said, with help from the United States, Jordan, Britain and other allies.