In a statement, Gaza's Government Media Office said doctor assessments suggested that third-degree burns on the bodies of patients, many of who died, were caused by the weapons used by the Israeli army.
The arms were mainly US-made, known as chemical or thermal weapons, and "are internationally prohibited from being used against humans," the statement added.
It held the US government full responsible legally for providing Israel with such weaponry.
The Israeli army and the US administration are yet to comment on the statement.
Israel, flouting a UN Security Council resolution demanding an immediate cease-fire, has faced international condemnation amid its continued brutal offensive on Gaza since an Oct. 7 attack last year by the Palestinian group Hamas.
Nearly 38,700 Palestinians have since been killed, mostly women and children, and more than 89,000 injured, according to local health authorities.
More than nine months into the Israeli onslaught, vast tracts of Gaza lie in ruins amid a crippling blockade of food, clean water and medicine.
Israel is accused of genocide at the International Court of Justice, whose latest ruling ordered it to immediately halt its military operation in the southern city of Rafah, where more than 1 million Palestinians had sought refuge from the war before it was invaded on May 6.