The defender found himself in trouble with caretaker manager Terry Connor on Monday morning, the day after a 5-0 defeat at Fulham when he was one of the substitutes.
Connor said on www.wolves.co.uk: "I can confirm that Roger was involved in a breach of club discipline on Monday, for which he has apologised and accepted his punishment."
He added: "The matter has been resolved internally and the club will be making no further comment."
Johnson, who was signed from Birmingham last summer after their relegation from the Barclays Premier League, has found himself out of favour since Connor replaced the sacked Mick McCarthy at the helm two weeks ago.
He has struggled to reproduce the form he demonstrated at Blues alongside Scott Dann since his switch to Molineux.
Johnson said: "My conduct and approach to training on Monday was below the high standard the club rightly needs and demands of me, and what I demand of myself.
"As a result of that I have apologised to the manager, my team-mates and the club."
Source: PA
Source: PA