The US has said it is not directly involved in Israel's campaign, but it is a key supplier of missiles and technology for its ally's sophisticated air defences systems.

Reports have also said that American military assets in the Middle East, including a Navy destroyer, have helped shoot down Iranian ballistic missiles.

"I want to thank President Trump, a great friend of the state of Israel," Netanyahu said in a televised statement.

"I thank him for being at our side, and I thank him for the support of the United States in defending Israel's skies."

After decades of enmity and a violent shadow war, fighting between the longtime foes erupted Friday when Israel launched a wide-ranging bombing campaign that prompted Iran to hit back with missiles and drones.

Trump has appeared to flirt with the idea of joining Israel's campaign in his public remarks in recent days -- even going so far as to call for Iran's "unconditional surrender" -- but said Wednesday that he had not yet made a decision on whether to take part.

Netanyahu, meanwhile, said Israel was targeting Iran with "tremendous power", while acknowledging that Israel had suffered "painful losses" in the war.

"We are hitting their nuclear programme, their missiles, their military headquarters, the symbols of their power," he said.

"We are suffering numerous losses, painful losses," he added. "But the home front is solid, the people are strong and the state of Israel is stronger than ever."

Since Friday, at least 24 people have been killed in Israel and hundreds wounded, according to Netanyahu's office.

Israel's air defence systems appear to have been largely successful in intercepting the daily barrages of Iranian missiles and drones.

An Israeli military official, who asked not to be named, said Wednesday evening that Iran had fired around 400 ballistic missiles and 1,000 drones since Friday.

About 20 missiles had struck civilian areas in Israel, the official added.

Media outlets in Israel are subject to strict restrictions from the military on the reporting of Iranian air strikes.

Iran said on Sunday that Israeli bombing had killed at least 224 people since fighting began, including military commanders, nuclear scientists and civilians. It has not issued an updated toll since then.