The Bosnian striker came off the bench against Tottenham Hotspur at the Etihad Stadium on Sunday to score a late winner in their 2-1 triumph in the Premier League.
"We haven't called him 'super sub'," BBC Sport quotes Platt as saying. "That's just what people want to call him.
"I wouldn't say it is his best role. It's not whether he scores after coming off the bench, it's whether he scores when he is on the field.
"We can only pick 11 players and pick players on the bench to come on. That's the way it has been in the time I have been here and it is the same at every club."
Platt added that Dzeko is one of the important players for City.
"Against Tottenham, we felt we needed an injection of something different up front, a little more height to get the ball and hold it up," he said.
"But we also know Edin is a goal threat. He has scored a lot of goals this season and a lot of goals since he signed in January last year.
"He has got what I would call 'heavy' - or important - goals for us and he is a valued member of our squad."
City are currently second in the Premier League table with 25 points from 11 matches, two points behind leaders Manchester United.