A UN investigation report said that a wedding had in fact taken place and had "gathered about 100 civilians at the site of the strike." France rejected the findings, saying it had killed armed militants.
A French air strike had killed at least 19 civilians in central Mali in January, according to a UN report, which added that the victims were protected under international law.
On January 3, French warplanes struck near the remote village of Bounti in circumstances that sparked controversy in the war-torn Sahel state.
Residents of the village said the strike hit a wedding party and killed civilians.
But France's military rejected the accusation and said it had killed "jihadists". It also denied that a wedding had taken place in Bounti that day.
The United Nations mission in Mali, known as MINUSMA, subsequently launched an investigation into the affair.
In a report summarising the probe's findings, the UN said a wedding had in fact taken place and had "gathered about 100 civilians at the site of the strike".
It added that about five armed people, who are thought to be members of the militant group Katiba Serma, attended the celebrations.
At least 22 people died in the French strike, of whom 19 were civilians, according to the probe.
"The group affected by the strike was overwhelmingly composed of civilians who are protected persons under international humanitarian law," the report said.
"This strike raises serious concerns about respect for the principles of the conduct of hostilities," it added.
The UN report is based on 115 individual interviews and constitutes a rare criticism of the actions of French forces in Mali.
Investigators also conducted group interviews and about 100 telephone interviews.
Mali has been struggling to contain an insurgency which first broke out in the north of the country in 2012 before spreading to the centre and neighbouring Burkina Faso and Niger.
France, the former colonial power, intervened in Mali in 2013 to beat back the militants, and now has some 5,100 soldiers deployed across the semi-arid Sahel region.
Central Mali, where the strike on Bounti occurred, is an epicentre of the brutal conflict.