Later in Israel, thousands joined the families of hostages still being held by Hamas to demand that Prime Minister Benjamin Netanyahu negotiate an end to the war.
There were protests in Jerusalem and in Tel Aviv, where a large black banner was unfurled imploring US President Donald Trump to help end the war, with "SAVE THEM!" in yellow letters.
The latest military strikes come as some prominent Western countries prepare to recognise Palestinian statehood at the gathering of world leaders at the United Nations General Assembly next week. They include Australia, the UK, France, Canada, Malta, Belgium and Luxembourg.
The latest Israeli operation, which began this week, further escalates a conflict that has roiled the Middle East and likely pushes any ceasefire further out of reach.
The Israeli military, which says it wants to "destroy Hamas' military infrastructure" and urged Palestinians to leave, hasn't given a timeline for the offensive, but there were indications it could take months.
Israeli bombardment over the past 23 months has killed more than 65,000 people in Gaza, destroyed vast areas of the strip, displaced around 90 per cent of the population and caused a catastrophic humanitarian crisis, with experts saying Gaza City is experiencing famine.
Rami Mhanna, the managing director of Shifa Hospital, where some of the bodies were brought, said the dead included six people from the same family after a strike hit their home early on Saturday. They were relatives of the hospital's director, Dr Mohamed Abu Selmiya, he said.
The Palestinian Red Crescent said five others were killed in another strike close to Shawa Square.
Israel's military said it couldn't comment on the specific strikes without more information, but that it was "operating to dismantle Hamas military capabilities" and "takes feasible precautions to mitigate civilian harm".
Israel has been urging hundreds of thousands of Palestinians sheltering in Gaza City to move south to what it calls a humanitarian zone and opened another corridor south of Gaza City for two days this week to allow more people to evacuate.
Palestinians were streaming out of Gaza City by car and on foot, though many in the famine-stricken city are unwilling to be uprooted again, too weak to leave or unable to afford the cost of moving.
Along the coastal Wadi Gaza route, those too exhausted to continue stopped to catch their breath and give their children a much-needed break from the difficult journey.
Aid groups have warned that forcing thousands of people to evacuate will exacerbate the dire humanitarian crisis. They are appealing for a ceasefire so aid can reach those who need it.
Families of hostages still held by Hamas accused Netanyahu of condemning their loved ones to death by continuing to fight rather than negotiate an end to the war.
"The blood of our loved ones is, for him, nothing more than a political tool to cling to power," they said in a statement read outside Netanyahu's residence. "As long as there is war, Netanyahu has a government."
Forty-eight hostages remain in Gaza, with fewer than half believed to still be alive. Hamas-led militants stormed into southern Israel on October 7, 2023, killing around 1200 people, mostly civilians, and abducting 251 others.
