Glentoran Football Club said it will "act decisively" on those involved in clashes after the weekend's Larne game at the Oval.
There was fighting between fans after the east Belfast club's 1-0 defeat and crowds gathered after the game outside the ground calling for manager Mick McDermott to be sacked.
Police were in attendance.
The club have won just one of their last 10 fixtures. Glentoran said the results did not justify lawless behavior from supporters.
"The Directors of Glentoran recognise that our performances on the pitch have fallen below what is acceptable to the club and our fans," Glentoran said in a statement.
"Our duty is to address this urgently.
"We understand the frustration and concerns. This does not however give anyone the right to break the law or make our ground an unsafe place for fans and officials.
"Incidents of violence, criminal damage and threats of harm occurred after yesterday's match that are totally unacceptable.
"Over the next few days, we will be reviewing CCTV footage and taking statements from people who were present.
"Where we find individuals involved in violence, threats of harm or criminal damage we will act decisively in the interest of our club, our fans, our volunteers and our employees."
Police were in attendance at Saturday's game to provide support.
"There was protest activity reported in the car park and officers attended to monitor the situation. No arrests were made and enquiries are continuing," a PSNI statement said.
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