A UN-backed report recently warned that there was an imminent likelihood of famine in northern Gaza, where hardly any aid has entered in the past month.
Joyce Msuya, the United Nations acting under secretary general for humanitarian affairs, said international crimes were being committed in Gaza.
Ms Msuya briefed council members at the United Nations on Tuesday, reporting that Israeli authorities were blocking humanitarian assistance from entering North Gaza, where fighting continues.
She said 75,000 people remain there with dwindling supplies.
Last month, US Secretary of State Antony Blinken gave Israel 30 days to ensure more aid trucks reached Gaza daily. That deadline expired on Tuesday.
A letter sent to the Israeli government demanded the country end the isolation of the besieged north, where aid groups warn that civilians are being starved amid Israel’s military offensive.
A group of eight humanitarian aid agencies said conditions had actually deteriorated since the letter was sent.
But the US reaction on Tuesday indicates that Washington will continue to supply weapons to its ally, despite growing warnings from aid groups about civilians being killed and displaced by Israel’s assault on the north.
The Israeli military, however, said it has been routing a Hamas resurgence in the region.
Israel says it has substantially increased the amount of aid getting into Gaza, and accuses aid agencies of failing adequately to distribute it.
In Beit Hanoun, which was besieged for more than a month, Ms Msuya said food and water reached shelters Monday only for Israeli soldiers to forcibly displace people from those areas Tuesday.
Ilze Kehris, assistant secretary general for human rights at the UN, said the pattern and frequency of Israel's attacks suggest systematic targeting of civilians.
Much of the death and destruction was caused by US weapons, given to Israel in order the help the fight Hamas.
Israel launched a campaign to destroy Hamas after the group's attack in southern Israel on 7 October 2023, which left about 1,200 people dead; 251 others were taken hostage.
Since then, more than 43,000 people have been killed in Gaza, according to the territory's Hamas-run health ministry.