Heskey, who has been linked with a move to former club Leicester, will return to the Villa squad for Sunday's FA Cup clash at Arsenal after a spell on the sidelines with an Achilles problem.
The current contract of the former England player runs out in May, and McLeish said: "We realise that this is a transitional period at the club so it is not right for us to make any quick decisions. The overall position is that we'll review things at the end of the season."
He added: "It's up to guys like big Emile to produce a few good performances between now and the end of the season by banging in a few goals, getting a few assists, and then we can address it at that time.
"From what I've seen in training this morning, I would certainly say he will continue to give everything. Emile is a guy who gives everything and does everything he can for the team.
"Will he go back to Leicester in the summer? I haven't got a clue."
Heskey continued to make himself available for selection despite the Achilles setback until it became too serious to continue.
McLeish said: "We've just been kind of managing him and allowing him to make an impact as a sub or for a certain amount of time in games.
"It just became a bit intolerable for him but he's had a few scans and injections. He's fit to play."