The Inter Milan goalkeeper, who has 34 caps for the Indomitable Lions, started their 1-0 defeat to Switzerland in their opening World Cup game before clashing with head coach Rigobert Song over his playing style.
Onana preferred to play out from the back as evidenced by his 26 touches outside the box against the Swiss but Song wanted a less risky approach.
Onana's name was conspicuously missing from the team sheet for Cameroon's 3-3 draw with Serbia on Monday, with Devis Epassy chosen to start between the sticks.
The Cameroon Football Federation has thrown more light on Onana's absence, with disciplinary reasons cited for his removal from the squad.
"Following Rigobert Song's decision, Andre Onana has been temporarily suspended from the group for disciplinary reasons," a statement read.
"The Cameron Football Federation reiterates its full support to the head coach and his entire staff as they implement the Federation's policy aimed at preserving discipline, solidarity, complementarity and cohesion within the national team.
"FECAFOOT further reaffirms its commitment to create a peaceful atmosphere for the team and to provide them with adequate facilities for outstanding performance."
Cameroon will need to win against Brazil in their final group game to stand any chance of advancing into the knockout rounds.
