Since the Bosnia-Herzegovina international's £27million move from Wolfsburg last month he has scored two goals - both against League One side Notts County - in eight appearances.
Dzeko said: "It's harder here but I will get used to it. It is something new for me."
He added: "The referees don't whistle for everything here - in the Bundesliga every small contact is a foul.
"The coach (Roberto Mancini) says to me it is different in Italy and Germany as the referees whistle everything.
"I hope I can get used to it, and have to get stronger. I have to play stronger.
"In some situations in Germany where I am not so strong it is no problem but in England it is different. You have to fight for every ball.
"I am okay mentally. When I don't score for two or three games and then lose the ball I always keep my head up."