The Prime Minister and US president, along with the leaders of France, German, Italy and Canada, called for Israel to respect international humanitarian law, demanded the release of the hostages held by Hamas and pushed for aid for Gaza.
The joint call came as the conflict threatened to spread as Israel continues preparations for a ground offensive in Gaza.
Israel continued to strike targets across Gaza over the weekend and also targeted two airports in Syria and a mosque in the occupied West Bank allegedly used by militants.
Israel has traded fire with Lebanon’s Iran-backed Hezbollah militant group on a near-daily basis since the war began and the US is also wary of Iran’s proxies being used to spread violence throughout the region.
In the latest sign of the intensive diplomatic effort to manage the situation, Mr Sunak, Mr Biden, France’s Emmanuel Macron, Germany’s Olaf Scholz, Italy’s Giorgia Meloni and Canada’s Justin Trudeau spoke on Sunday night.
A Downing Street spokeswoman said: “The leaders reiterated their support for Israel and its right to defend itself against terrorism and called for adherence to international humanitarian law, including the protection of civilians.
“They welcomed the release of two hostages and called for the immediate release of all remaining hostages.”
The first aid convoys reached Gaza through the border with Egypt over the weekend, 20 trucks on Saturday and 14 on Sunday.
But the United Nations said much more was needed and the Rafah border crossing is still not open for foreign nationals seeking to flee bombarded and besieged Gaza.
The No 10 spokeswoman said the leaders “committed to close co-ordination to support their nationals in the region, in particular those wishing to leave Gaza”.
“The leaders welcomed the announcement of the first humanitarian convoys to reach Palestinians in need in Gaza and committed to continue co-ordinating with partners in the region to ensure sustained and safe access to food, water, medical care, and other assistance required to meet humanitarian needs.”
In a sign of how seriously the risk of the war spilling over is being taken, the leaders “committed to continue close diplomatic co-ordination, including with key partners in the region, to prevent the conflict from spreading, preserve stability in the Middle East, and work toward a political solution and durable peace”.