Preston have been hit with a £10,000 fine by the Football Association following the crowd trouble at their play-off game against Chesterfield last season.
North End sealed their place in the League One final with a 3-0 victory at Deepdale, but there were ugly scenes during a pitch invasion after the final whistle.
Chesterfield defender Ian Evatt, who used to play for Preston's fierce rivals Blackpool, was assaulted by a supporter who was later given a three-year ban from football.
An FA statement read: "Preston North End have been fined £10,000 and warned as to their future conduct following crowd incidents at Deepdale on May 10, 2015.
"An independent regulatory commission found that a breach of FA Rule E20 alleging that the club failed to ensure that its spectators or persons purporting to be its supporters or followers refrained from provocative and/or abusive and/or threatening and/or violent behaviour whilst attending the fixture against Chesterfield FC was proven."