Key ally the United States – which reported 11 of its own citizens killed and many more missing in the escalating conflict – stressed its full support for Israel, as did Britain, France, Germany and Italy.
Five Western powers and several other countries have reported their citizens killed, kidnapped or missing, including Brazil, Cambodia, Canada, Ireland, Mexico, Nepal, Panama, Paraguay, Russia, Thailand and Ukraine.
Hamas is holding about 150 people hostage, including children, elderly and young people, since its ground attack that killed some 270 people at a music festival.
On Monday, Hamas warned that it would begin killing hostages whenever Israel attacks a civilian target in Gaza without warning.
Fear and chaos are rampant among the 2.3 million Palestinians who live in the crowded and impoverished coastal region that has been hit by thousands of Israeli bombs.