Stena Line has banned Glasgow Rangers supporters travelling as foot passengers from its sailings between Northern Ireland and Scotland.
There was trouble between Rangers and Celitc fans on the ferry
The ferry company said it had taken the decision following trouble involving supporters on a sailing on Saturday.
Trouble broke out as Rangers and Celtic fans returned from an Old Firm derby match, which Rangers won 3-1.
Rangers said indefinite and lifetime bans would be considered against anyone who brought the club into disrepute.
Jim McGreevey, whose mother was on board the ferry on Saturday, said that she had been terrified by the sectarian behaviour.
"The supporters, they weren't even singing football songs, it was about killing Catholics, and named Catholics that have been shot dead," he told BBC Radio Ulster's Nolan Show.
"Then one of the Stena Line staff came down and asked them to be quiet, this seemed to up the ante and they just got out of control."
The ban will cause problems for Rangers fans next Wednesday as the team is due to play in a Champions League qualifier in Glasgow.
Stena Line said the ban would begin immediately, but would not affect those who travel with clubs, most of which travel by bus and are registered.
The ban will only apply to individuals or small groups who are not registered as clubs and travel as foot passengers.
It said those involved in the "loutish behaviour" were a minority of Rangers supporters, but that such behaviour would not be tolerated.
"We are taking this action for the well being of all our passengers, many of whom are families with children, and none of whom should be subjected to sectarian or offensive behaviour," it said.
"We would also like to point out that every week, Stena Line carries thousands of supporters on its five Irish Sea routes to soccer and rugby matches in Scotland, England and Wales - without incident."
In a statement, a Rangers spokesperson said the club was "unaware" of the incident on Saturday and had not been contacted by Stena Line.
"The club vigorously promotes its Pride Over Prejudice initiative which appeals to fans to show respect and courtesy to the general public whilst travelling to and from matches on public transport," it said.
"It is unfortunate if those who don't participate in sectarian behaviour also find themselves affected by the unacceptable behaviour of a minority."