Israel's military chief said Monday that the country will respond after Iran launched an attack involving hundreds of drones, ballistic missiles and cruise missiles. World leaders are urging Israel not to retaliate.

British Prime Minister Rishi Sunak says "all sides must show restraint" to avoid a rising spiral of violence in the Middle East. French President Emmanuel Macron said Paris will try to "convince Israel that we must not respond by escalating."

The Iranian attack on Saturday marked the first time Iran has launched a direct military assault on Israel, despite decades of enmity dating back to the country's 1979 Islamic Revolution. The attack happened less than two weeks after a suspected Israeli strike in Syria that killed two Iranian generals in an Iranian consular building.

An Israeli military spokesman said that 99% of the drones and missiles launched by Iran were intercepted.

Israel and Iran have been on a collision course throughout Israel's six-month war against Hamas militants in the Gaza Strip. The war erupted after Hamas and Islamic Jihad, two militant groups backed by Iran, carried out a devastating cross-border attack on Oct. 7 that killed 1,200 people in Israel and kidnapped 250 others.

An Israeli offensive in Gaza has caused widespread devastation and killed over 33,700 people, according to local health officials.