"Fassbender was politely asked to leave. He was in good spirits but it was becoming a bit of a handful for the other guests," a source told British newspaper The Sun.
"He was grabbing his co-stars and waltzing around the room with them. He lit a cigarette indoors and that was the point it had gone too far.''
However, MailOnline reports that both Fassbender and Knightley decided to show off their moves together and turned the dining area into a makeshift dancefloor.
According to the publication "the two co-stars couldn't resist putting on a show for onlookers" as they moved around the restaurant.
At one point, Fassbender even tried a complicated dance move as he "draped Keira over his arm and bent her backwards''.
Knightley clearly enjoyed herself during the evening. She was seen laughing and kissing her boyfriend, musician James Righton, as they left the party together.