Latics winger Cristian Montano was one of six players to be arrested as part of a National Crime Agency (NCA) investigation following claims by The Sun newspaper that a Championship game had been fixed.
Former Portsmouth defender Sam Sodje and Blackburn striker DJ Campbell are also among those to be arrested.
However, five of the six players have now been bailed until April 2014.
Asked about Montano's involvement, Johnson told Oldham's official club website: "Anybody who saw that report will have been devastated and sick to their stomachs.
"However, we have to let the authorities do their job and duties, and we cannot prejudice that.
"The reason why I am in it is because there are so many great people around place and who are giving everything to the cause.
"There are volunteers who we see everyday in the corridors, the players who give everything they can, staff who work all hours when they are understaffed for the jobs they are trying to do and the stewards who are paid a minimal amount but who work extremely hard and provide safety for everyone.
"And last but not least the fans who are fantastic spending their hard-earned money in hard times to travel all over the country to watch and support us.
"There is a lot to celebrate about this club, and we have to make sure we don't forget that."
Johnson added the club will have to wait for the results of the investigation before they can determine Montano's future.
He added: "It is disappointing how somebody can get themselves into that situation.
"The truth is that we don't know yet what has happened for him to be in the room talking about that.
"I feel we have to step back and, as manager, it is my job to rally the troops and I am sure the players have that desire for three important games in the next 10 days.
"We have to use whatever we can to get the best out of the situation and hopefully that starts with a show of unity tomorrow from the club, the players and the fans."