"The United States has been clear we would not support any measure that fails to condemn Hamas and does not call for Hamas to disarm and leave Gaza," Acting US ambassador to the UN Dorothy Shea told the council before the vote.
"This resolution would undermine diplomatic efforts to reach a ceasefire that reflects the realities on the ground, and embolden Hamas," she said of the text that was put forward by 10 countries on the 15-member council.
The remaining 14 council members voted in favour of the draft resolution.
Israel has rejected calls for an unconditional or permanent ceasefire, saying Hamas cannot stay in the Gaza Strip.
It has renewed its military offensive in the enclave - also seeking to free hostages held by Hamas - since ending a two-month ceasefire in March.
Gaza health officials said Israeli strikes killed 45 Palestinians on Wednesday and Israel said a soldier died in fighting.
A humanitarian crisis also grips the enclave of more than two million people: famine looms and aid has only trickled in since Israel lifted an 11-week blockade on May 19.
No aid was distributed by the US-backed Gaza Humanitarian Foundation on Wednesday as it pressed Israel to boost civilian safety beyond the perimeter of its so-called secure distribution sites after a deadly incident.
The GHF said it has asked the Israeli military to "guide foot traffic in a way that minimises confusion or escalation risks" near military positions; develop clearer guidance for civilians; and enhance training to support civilian safety.
Hospital officials have said more than 80 people were shot dead and hundreds wounded near distribution points in a three-day period from Sunday, including at least 27 killed on Tuesday.
Locals said Israeli soldiers opened fire on the crowd on Tuesday that massed before dawn to seek food.
The military has denied this but acknowledged that troops fired at "suspects" who ignored warning shots and were approaching their lines.
"Our top priority remains ensuring the safety and dignity of civilians receiving aid," a GHF spokesperson said.
The new aid distribution process - currently from just three sites - was launched last week.
The UN and other aid groups say the model, which uses private US security and logistics workers, militarises aid.
The war in the Gaza Strip has raged since 2023 after Hamas militants killed 1200 people in Israel in an October 7 attack and took about 250 hostages back to the enclave, according to Israeli tallies.
Many of those killed or captured were civilians.
Israel responded with a military campaign that has killed more than 54,000 Palestinians, according to Gaza health authorities.
They do not distinguish between fighters and non-combatants but say civilians have borne the brunt of the attacks and that thousands more bodies have been lost under rubble.
