Speaking alongside the Israeli prime minister in Tel Aviv on Thursday afternoon, Sunak also praised Netanyahu for taking steps to allow some aid to get into Gaza.
“I’m proud to stand here with you in Israel’s darkest hour, as your friend,” Sunak said.
“We will stand with you in solidarity, we will stand with your people. And we also want you to win.”
He added: “I know you are taking every precaution to avoid harming civilians in direct contrast to the terrorists of Hamas which seek to put civilians in harm’s way”.
Downing Street said this morning that at least seven British nationals have been killed while a further nine are missing.
Describing Hamas as “the worst monsters on the planet”, Netanyahu told Sunak: “Eighty years ago, prime minister, the civilised world stood with you in your darkest hour.
“This is our darkest hour. It’s the world’s darkest hour. We need to stand together. We must win together.”
Sunak’s visit to the region comes as the region reels from a massive blast at a hospital in Gaza.
It has increased fears the war, which began when Hamas launched a surprise attack on Israel earlier this month, could escalate into a wider conflict.
Hamas has blamed the hospital blast - which it said killed at least 500 people - on an Israeli airstrike.
The Israeli military has blamed a misfired rocket by Palestinian militant group Islamic Jihad.
Joe Biden, who landed in Israel on Wednesday morning, has said the blast was caused by “the other team”, not Israel.
But the British government has said it will not “rush to judgement” over who was responsible and is still investigating.
More than 1,400 people in Israel have been killed as a result of Hamas’ October 7 attack. The militant group also still holds more than 200 hostages.
The Gaza Health Ministry has said at least 3,200 people have been killed in Gaza so far during Israeli retaliatory strikes.