Referee Roger Furnandiz stopped play to discuss the situation with the other officials, and warnings were shortly given out over the public address system. Furnandiz is expected to include the incident in his match report.
This is just the latest in a long list of problems the club has had with a minority group in the 'Kempton' stand. City were already on a 'last warning' over coin-throwing, while racial chants have also stirred up difficulties.
The FA are waiting on the referee's report before making an announcement.