On its Web site, the team noted that the three-year veteran is facing six misdemeanor counts of possession of a firearm without a valid Illinois Firearm Owner's Identification card.
The charges stem from an incident on Thursday, when the Gurnee (Ill.) Police Department executed a search warrant at Johnson's home.
"We're disappointed in the situation that's come up right now," said Coach Lovie Smith upon learning about the incident. "It's a distraction for the (11-2) team and all of that. I'll get more details and go from there."
It is the second time this year that Johnson has been involved in a questionable situation.
Last March, prosecutors dropped battery and resisting arrest charges filed against him stemming from an incident the month before outside a Chicago nightclub.
That arrest violated his probation resulting from a guilty plea to a misdemeanor unlawful gun possession charge.