Football's world governing body sent its deepest sympathies to the families and friends of the victims of the crush at the Africa Cup of Nations.
Because of Covid-19 restrictions, the Olembe Stadium was not meant to be more than 80% full.
As many as 50,000 people were trying to attend the match, according to match officials.
"Fifa sends its deepest condolences to the families and friends of the victims who lost their lives following the tragic incident that took place at Olembe Stadium," the statement from Fifa said.
The thoughts and prayers of the global football community are with the victims, the ones who have been injured in this incident, and all the staff of both the Confederation of African Football (Caf) and the Cameroonian Football Association (Fecafoot) at this difficult moment.
The local organizing committee of the Nations Cup is being investigated by the organizers.
The general secretary visited injured supporters in the hospital.
Eric Djemba-Djemba attended the last-16 game and said the news of the incident was heartbreaking.
The 40-year-old, who had a spell at Manchester United from 2003 to 2005, told the World Service that it was shocking as people were coming to the stadium to watch football.
We heard people had died outside of the stadium.
It is the worst possible news because the tournament was held in Cameroon and the stadiums were built. I think it is very sad.
It will be hard for people to focus on the tournament because families will cry. It is the worst thing to happen to a country when people go to the stadium to support their team.