The Dons selected Jake Nicholson in the matchday squad for their Sky Bet League Two clash with Cheltenham on March 22 and he came on as a substitute at half-time, scoring as they went on to win 4-3
Following a Football Disciplinary Commission on Monday, they were docked three points and fined £5,000, suspended until the end of next season.
The deduction sees Neal Ardley's side drop from 14th to 18th in the table, but they are not in danger of relegation with only one game to play
Chief executive Erik Samuelson spoke of the club's regret at the situation but confirmed they would not be looking to overturn the decision
"We feel that the club had a fair hearing and, while very disappointed with the result, have no intention of appealing against the decision of the Football Disciplinary Committee," he told the club's official website
"The Football Club Board greatly regrets that this situation arose and apologises for the uncertainty and distress that it has caused to supporters in the days since the hearing was announced."
Source : PA