Palestinian leader Mahmoud Abbas has accused Israel of waging a "war of genocide" in Gaza and vowed to pursue its leaders for war crimes.
The latest war in Gaza in July and August - the third war in the Gaza Strip in six years - killed 2,140 Palestinians, mostly civilians.
"We will not forget and we will not forgive, and we will not allow war criminals to escape punishment," Abbas said in a speech to the UN General Assembly on Friday.
The address angered the United States, which slammed it as "offensive," while Israeli Foreign Minister Avigdor Lieberman accused Abbas of waging "diplomatic terrorism" and making "false accusations".
The speech was seen as one of the strongest during the Abbas' decade as Palestinian president.
"Israel has chosen to make it a year of a new war of genocide perpetrated against the Palestinian people," he said.
The war in Gaza was "a series of absolute war crimes carried out before the eyes and ears of the entire world," he said, citing the destruction left behind and the deaths of more than 460 children.
The Palestinians have threatened to join the Hague-based International Criminal Court to allow legal action to be taken against Israel.
The US State Department reacted with a tersely worded statement, saying the speech would undermine peace efforts.
"President Abbas' speech today included offensive characterisations that were deeply disappointing and which we reject," said spokeswoman Jen Psaki.
"Such provocative statements are counterproductive and undermine efforts to create a positive atmosphere and restore trust between the parties," she said
The war ended on August 26 when the two sides agreed in Cairo on a ceasefire and to hold future talks on Palestinian demands to end an eight-year blockade of Gaza.
In his speech, Abbas also said he will seek a UN resolution to set a deadline for Israel to pull out of Palestinian lands captured in the 1967 war. He included no deadline for ending the occupation.