John Tonnes of Nordisk Film cinemas told The Copenhagen Post the sign was apparently misunderstood and he's sorry that it caused trouble.
The sign, posted in the window of Copenhagen's Palads Theater, warned patrons that due to the end of the Muslim fasting month of Ramadan Saturday, more Muslims than normal would be in the theaters. It went on to say that they could get loud, annoying other movie watchers.
The sign offered advice on which films would attract the most Muslims.
"G4S guards will be available all day, so if you experience unacceptable behavior, please contact them," the sign advised.
The sign prompted a storm of criticism on Facebook and Twitter.
Tonnes said the Palads employee who posted the sign only wanted to warn patrons that there would be more noise than usual.
"It's the type of thing that could be misunderstood and perceived as offensive," Tonnes said.