During the second half of the Red Devils's 2-1 win over the Citizens, there was an incident where United's Fred was struck by an object thrown from the crow.
Footage surfaced on social media showing a suppporter allegedly making monkey gestures towards the United players.
When asked by Sky Sports if the abuse affected him, Rashford said, "No, not during the game but it can happen.
"In recent times, we have been dealing with it a bit better but the fact it is still happening isn't good enough.
"There is obviously still some work to do in that area.
"But for us, it is about the football and what we do on the pitch."