Volker Finke's team initially refused to travel to Brazil for the World Cup due to a disagreement over how much the players would be paid, forcing them to arrive at their tournament base late.
Players and coaching staff were quick to downplay the situation upon arrival in South America, insisting the team's preparations for the competition were not dented as a result.
However, after defeats to Mexico and Croatia brought about Cameroon's elimination from Group A, Mbia has conceded the row looks to have had an influence.
"You have to be objective and realistic; that (the bonus row) has played a role," he is quoted as saying in AS.
"In a great worldwide tournament, certain rules must be respected and we paid for our mistakes. No one wanted to do so badly.
"Despite what you people think, we are very united. There are no conflicts, no problems.
"We are simply disappointed by not getting good results despite all of our work and the very good things in training.
"It's a matter of pride, as an African and as a Cameroonian. We must improve our image and not finish like we did in 2010 when we ended catastrophically, with zero points."
Cameroon face hosts Brazil in their final group game on Monday.
