The incident was sparked by the yellow carding of three Montferrand forwards by referee Rob Dickson during the last ten minutes of their home Pool Five match against Cardiff in October.
Chairman of the European Rugby Cup disciplinary committee, RFU delegate Terry Burwell, said: "The responsibility for the safety of the match officials is with the clubs.
"It is essential that the match officials are protected from physical and verbal abuse.
"ERC is committed to ensuring that match officials are free to carry out their duties and that the integrity of the tournament is both maintained and safeguarded."
The fine is suspended for the rest of the 2001-2002 season – subject to no further misconduct on the part of the club, its players, officials and supporters.
The costs of the hearing, which was held in Dublin on Tuesday, will also be met by Montferrand, although the club has the right of appeal.
