Chesterfield supporters invaded the pitch during and after the game at the b2net Stadium on April 25, when victory for the Spireites against the second-placed Shakers would have seen them clinch the League Two title.
One fan who punched Belford in the face was subsequently arrested after being caught in the act by a press photographer at the game.
Chairman Barrie Hubbard said: "In football terms we have been yellow carded but it could have been so much worse because the FA has a wide range of sanctions at its disposal.
"The strong line the club has taken in conjunction with the police, and the clear warning to fans about future behaviour, which was so impeccably observed at the Gillingham game, has clearly all been taken into account.
"The fans have shown they can behave and celebrate in a responsible manner and this has set the standard now expected at all future matches."
Source: PA
Source: PA