Nottingham Forest will launch an investigation after Derby’s Bradley Johnson was jostled by a pitch invader after Friday’s Sky Bet Championship encounter.
Nelson Oliveira’s early strike proved the difference at the City Ground as the Reds ran out 1-0 victors against their in-form rivals.
It ended Forest’s eight-match winless streak and led to celebrations spilling on to the pitch after the final whistle.
One of the fans made a beeline for Derby midfielder Johnson, who was forced to push him away forcefully, and Forest have promised to investigate the incident.
Earlier on Friday, Preston were hit with a £10,000 fine by the Football Association following the crowd trouble at their play-off game against Chesterfield last season.
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.