UN Secretary-General Antonio Guterres condemned the unintentional Israeli air strike that killed seven aid workers from the charity World Central Kitchen in Gaza on Monday.
The victims were from Australia, Britain, Palestine, Poland, and the US-Canada.
Israeli Prime Minister Benjamin Netanyahu acknowledged the mistake.
This incident brings the total number of aid workers killed in the conflict to 196, including over 175 UN staff members.
Guterres urged for an immediate ceasefire between Israel and Hamas, calling the deaths "unconscionable." The UN Secretary-General,
António Guterres, expressed his concern over the continued violence in Gaza and the resulting civilian casualties.
He called the situation "unconscionable" and an "inevitable result" of the ongoing war.
Guterres urged for an immediate humanitarian ceasefire, the unconditional release of hostages, and the expansion of humanitarian aid into Gaza, as demanded by the recent UN Security Council resolution.
The resolution, which called for a ceasefire, was passed last week with the abstention of the United States, Israel's closest ally, sparking anger from the Israeli government.
Guterres' spokesman, Stephane Dujarric, also condemned the disregard for international humanitarian law and the protection of humanitarian workers in the region.