Bannan pleaded guilty at Nottingham Magistrates Court to drink-driving and three other offences and was also fined ?4,500. Villa plan to issue a statement on Bannan this afternoon, but McLeish made his feelings known at his media conference ahead of Sunday's game at Swansea.
He said: ""Hopefully this is a harsh lesson for him and it is also a warning to other players at the club, and the young players especially, in terms of growing up and trying to be a professional footballer."
He added: "Footballers are seen as role models. He has had a real shock, he has shown contrition, he is very ashamed of what happened.
"I'm certain we will see a different Barry Bannan in the coming months or years.
"From the outset we showed a tough stance on it (suspending Bannan) when we found out Barry had got into a little bit of trouble.
"We now have the verdict and the wee man has got to get on with his life and his football career."
McLeish confirmed Scotland international Bannan will be in contention for a place against the Swans.
He was initially left out of the squad against Sunderland while the club conducted an internal inquiry and also did not feature against Norwich, although he was available for selection.