Dundalk have banned four fans from Oriel Park following crowd trouble at the EA Sports Cup final.
The Lilywhites say the supporters, who were involved in skirmishes on the pitch at the end of their win over Derry, have "let the club down with their behaviour".
Dundalk have also confirmed they are continuing to investigate the incidents and could hand out more punishments.
The club said it does not condone any spectators invading the pitch, saying: "We are seeking to identify the perpetrators and, in particular, those who subsequently clashed with Derry City supporters on and off the pitch.
"Dundalk Football Club is proud to be an inclusive, family-orientated club. Anyone who wishes to behave in the way we sadly witnessed on Saturday is not welcome at the club. We do not need their support.
"We have already identified four of the main instigators, each of whom will receive lengthy bans from attending any matches at Oriel Park."
They have also appealed to supporters to help identify other troublemakers from the match.
They said: "If you have names, photos or social media footage of those people involved, please bring this to the attention of Dundalk Football Club to help with our investigations.
CLUB STATEMENT | #DundalkFC strongly condemns the behaviour of a small minority of supporters following Saturday’s EA SPORTS Cup final win over Derry City.September 16, 2019
"We would like to put on record our thanks to the overwhelming majority of supporters for their behaviour on Saturday night. You travelled a long distance for a late kick-off time in huge numbers and your loud and constant support of the team throughout the game was fantastic, as it has been all season.
"Furthermore, the anger that you directed at those who let the club down as they returned to the stand spoke for all true Dundalk supporters, whose reputation should not be tarnished by the behaviour of a small minority of troublemakers."