TV footage apparently showed Naismith catching Austin McCann in the face with an elbow during Saturday's 4-0 SPL win, although the Dunfermline defender played down the incident afterwards.
McCoist said: "I have seen it again but I've got nothing to say. We've not heard anything yet."
On a potential ban, the manager added: "It would definitely be a spanner in the works."
The SFA's Compliance Officer, if he decides there is a case to answer, has until 3pm on Tuesday to deliver a Notice of Complaint, together with evidence, to Rangers.