The UN Human Rights Council voted on Friday to set up a probe into recent killings in Gaza and accused Israel of excessive use of force.
The resolution to send a commission of inquiry to investigate was rejected by the United States and Australia, but backed by 29 members of the 47-state UN forum.
Another 14 countries, including Britain, Germany and Japan, abstained.
Israel's ambassador in Geneva, Aviva Raz Shechter, castigated the council for "spreading lies against Israel" during "five hours of ludicrous statements".
Palestinian Foreign Minister Riyad al-Maliki welcomed the UN decision.
“The Human Rights Council's formation of an international committee of investigation is a step towards doing justice to the Palestinian people,” he said in a statement. He urged speedy implementation "to stop Israeli war crimes".
The special session of the Human Rights Council was convened after the bloodiest day for Palestinians in years on Monday, when 60 were killed by Israeli gunfire during peaceful demonstrations against the US decision to move its embassy from Tel Aviv to Jerusalem.
"Nobody has been made safer by the horrific events of the past week," UN human rights chief Zeid Ra'ad al-Hussein said as he opened the debate.
Israeli forces had killed 106 Palestinians, including 15 children, since March 30, he said. More than 12,000 were injured, at least 3,500 by live ammunition.
Israel was an occupying power under international law, obliged to protect the people of Gaza and ensure their welfare, he said.
"But they are, in essence, caged in a toxic slum from birth to death; deprived of dignity; dehumanised by the Israeli authorities to such a point it appears officials do not even consider that these men and women have a right, as well as every reason, to protest."
The United States has stood by Israel during the past week's violence, which coincided with the opening of a new US embassy in Jerusalem.
US chargé d'affaires Theodore Allegra said the Council was ignoring the real culprit: Hamas.
"The one-sided action proposed by the council today only further shows that the Human Rights Council is indeed a broken body," he said.
Two million people live in Gaza, most of them stateless descendants of refugees who were forced out of their historic homes by Zionist gangs in 1948.
Israel has maintained an all-out siege on Gaza since 2007, leaving the vast majority of residents in abject need.
Israel has fought three wars against the militant group Hamas, which controls Gaza, leaving hundreds of Palestinians dead, thousands injured, and infrastructure in shambles.