Abbas said that Washington continued to provide diplomatic cover and weapons to Israel for its war in Gaza despite the mounting death toll there, now at 41,534 according to the health ministry in the Hamas-run strip.
"Stop this crime. Stop it now. Stop killing children and women. Stop the genocide. Stop sending weapons to Israel. This madness cannot continue. The entire world is responsible for what is happening to our people in Gaza and the West Bank," Abbas said in an address to the UN General Assembly.
The vast majority of the besieged Gaza Strip's 2.4 million people have been displaced at least once by the war, sparked by Hamas's October 7 attack on Israel, with many seeking shelter in school buildings.
"The US alone stood and said: 'No, the fighting is going to continue.' It did this by using the veto," he said, referring to the veto repeatedly wielded to thwart censure in the UN Security Council of Israel's campaign in Gaza.
"It furnished Israel with the deadly weapons that it used to kill thousands of innocent civilians, children and women.
"This further encouraged Israel to continuous aggression," he added, saying that Israel "does not deserve" to be in the UN.
Washington is Israel's closest ally and backer, supplying the nation with billions of dollars of aid and military materiel.
The October 7 attack that triggered the war resulted in the deaths of 1,205 people on the Israeli side, most of them civilians, according to an AFP tally based on official Israeli figures, which includes hostages killed in captivity.
Out of 251 people taken hostage that day, 97 are still being held inside the Gaza Strip, including 33 who the Israeli military says are dead.