The well-known American-Palestinian correspondent was shot and killed while reporting in the West Bank last month.
The UN human rights office has said that Al Jazeera journalist Shireen Abu Akleh was shot dead by Israeli troops, and not Palestinian forces.
The body said that Abu Akleh and her TV crew were hit by “seemingly well-aimed bullets” last month and has called for a criminal probe into her death.
The veteran Palestinian-American correspondent was shot and killed on 11 May while reporting on an Israeli military raid in the occupied West Bank town of Jenin.
Israel denies targeting her and has claimed she may have been hit by Palestinian gunfire.
But the UN human rights office said the shots that killed Abu Akleh and wounded a colleague, Ali Sammoudi, “came from Israeli security forces and not from indiscriminate firing by armed Palestinians.”
A spokeswoman for UN human rights chief Michelle Bachelet said her office had gathered information from witnesses, experts and official communications, as well as photos, video and audio material from the scene.
“We have found no information suggesting that there was activity by armed Palestinians in the immediate vicinity of the journalists,” said rights office spokeswoman Ravina Shamdasani.
"The journalists said ... that they proceeded slowly in order to make their presence visible to the Israeli forces deployed down the street," according to a UN press release.
"Several single, seemingly well-aimed bullets were fired towards them from the direction of the Israeli Security Forces."
"One single bullet injured Ali Sammoudi in the shoulder, and another single bullet hit Abu Akleh in the head and killed her instantly."
Shamdasani added that it was “deeply disturbing that Israeli authorities have not conducted a criminal investigation.”
Israel has long rejected the findings of UN bodies, accusing them of bias, and says they cannot determine who fired the fatal shot.
Defence Minister Benny Gantz said only a thorough, ballistic analysis of the bullet — which is held by the Palestinian Authority (PA) — could determine whether it was fired by Israeli troops or Palestinian militants.
The PA has refused to hand over the bullet and has accused Israel of trying to conceal its responsibility.
Israel has also denied allegations from Al Jazeera and the PA that Abu Akleh was deliberately targeted.