The former Rangers captain was no longer considered for international duty following incidents when on duty with his country last season.
But McLeish believes coping with the demands of the Premier League and international football at the age of 31 may mean him having to rest or rotate Ferguson on occasions.
He has been a key performer for Birmingham since making the switch from Rangers to again link up with McLeish during the summer.
McLeish said: "Would Ferguson welcome a return to playing for Scotland? I don't know but, if Barry was asked the question, he would be needed to be reminded he is in the Premier League and you need legs in this Premier League.
"If you are going to play every single game, you need to be super fit.
"To go and play international football at the age of 31 and to come back and perform week in and week out for us may mean there are times I'm going to have to rest or rotate him.
"He will have to consider that side of things. Am I being selfish? No, I am just guiding and educating him."
Ferguson will return after suspension for Saturday's home clash with Fulham.
He missed the 2-2 draw at Liverpool after being sent off for two bookable offences in the previous encounter with Manchester City.
McLeish believes Blues have set a standard which needs to be maintained in their last three games and has warned against complacency.
He said: "We have intensified training this week and we are looking for the players to get back to the same kind of tempo, the same kind of performance level of recent weeks.
"They have set the standards now and we will be demanding that type of performance from them every single week and they are capable of doing it.
"They have improved but, if they get complacent, they know what happens so it is up to the coaches and myself and the leaders in the team to keep on top of people and make sure that no-one is slacking."
McLeish has massive respect for Fulham boss Roy Hodgson and the "wonderful job" he has performed at Craven Cottage, but knows the expectancy levels will be higher for his team than against the 'bigger' teams in the Premier League.
He said: "It is a different pressure because when you play the likes of Man Utd, Liverpool, Arsenal, Spurs away you are maybe thinking we have nothing to lose and, if we lose the game, we won't get criticised too much.
"But now the likes of games against Fulham are the games we are judged on. The players have got to step up again and show they have the mentality to handle that.
"They can't all of a sudden get apprehensive about playing a home game and a team outside the top five or six.
"We've got to be going hammer and tongs, throwing everything at the opposition, particularly with it being at St Andrew's, and then I think we've got the ability to upset anyone at our place.
"It is quite simply one of these games where we have got to take advantage of playing at St Andrew's."