The report had been held up for several days amid debate within the State Department on whether to reprimand Israel, a historic US ally which has faced growing criticism over the toll in the seven-month Gaza war.
The State Department finally submitted its report two days after President Joe Biden publicly threatened to withhold certain bombs and artillery shells if Israel goes ahead with an assault on the packed city of Rafah.
The report does not affect that decision, with the White House reiterating Friday that it was concerned about Israeli military action around the southern Gaza city, where some 1.4 million Palestinians have taken shelter.
Biden, facing a furor over the war from within his Democratic Party months before elections, had in February issued a memorandum known as NSM-20 that asked countries that receive US military aid to make "credible and reliable" assurances they are complying with human rights laws.
Israel -- which launched a war against Hamas after the militants staged the deadliest ever attack on the country on October 7 -- made assurances to the United States and "identified a number of processes for ensuring compliance that are embedded at all levels of their military decision-making," said the public version of the report, which was submitted to Congress.
"The nature of the conflict in Gaza makes it difficult to assess or reach conclusive findings on individual incidents," it said.
"Nevertheless, given Israel's significant reliance on US-made defense articles, it is reasonable to assess that defense articles covered under NSM-20 have been used by Israeli security forces since October 7 in instances inconsistent with its IHL obligations or with established best practices for mitigating civilian harm," it said, referring to international humanitarian law.
- Accepting assurances -
The report also said that while the Israel Defense Forces have "the knowledge, experience and tools" to minimize harm, "the results on the ground, including high levels of civilian casualties, raise substantial questions as to whether the IDF is using them effectively in all cases."
But despite some "serious concerns," the report said that all countries receiving US military aid had made assurances credible and reliable enough "to allow the provision of defense articles covered under NSM-20 to continue."
A US official described the report as a snapshot and said the State Department would keep monitoring the use of weapons.
The other recipients of US military aid covered by the report were Colombia, Iraq, Kenya, Nigeria, Somalia and Ukraine.
Patrick Gaspard, president of the Center for American Progress, a left-leaning think tank, called the report disappointing, saying it ignored "overwhelming evidence" on Israel's actions.
"It's hard to believe that the administration sees what's happening in Gaza yet fails to conclude that Israel has violated the terms for use of American weapons," he said.
Republicans in turn have criticized NSM-20 since it was issued, saying it hinders Israel's campaign against Hamas and that the United States already has rules to deal with human rights.
- 'Deep concerns' on aid -
The report also stopped short of finding Israel in violation on another key concern -- humanitarian aid.
It said the United States had "deep concerns" over "action and inaction by Israel that contributed significantly to a lack of sustained and predictable delivery of needed assistance" to Palestinians.
But it said that the United States does not "currently assess that the Israeli government is prohibiting or otherwise restricting the transport or delivery of US humanitarian assistance."
The United Nations has warned of risks of famine in the Gaza Strip, where virtually the whole population has been displaced with a lack of consistent food, water or power.
The unprecedented attack on Israel on October 7 resulted in the deaths of more than 1,170 people, mostly civilians, according to Israeli figures.
Israel's retaliatory offensive has killed nearly 35,000 people in Gaza, mostly women and children, according to the health ministry in the Hamas-run territory.
