Eight people have been arrested following the Old Firm clash on Saturday.
A 23-year-old man has been arrested after allegedly running on to the pitch to confront Celtic captain Scott Brown at Ibrox Stadium in Glasgow.
Two men aged 36 and 16 were arrested in connection with allegedly trying to enter the ground while drunk while a 30-year-old man was held in connection with alleged offensive behaviour.
Three men aged 34 and 53 and a 15-year-old boy were arrested in connection with alleged breach of the peace while a 16-year-old was arrested for allegedly being in possession of alcohol at the ground.
Police are also investigating an alleged incident of racial abuse where someone allegedly made a monkey gesture at Celtic player Scott Sinclair.
A police spokesman said: "We are aware of that incident and inquiries are ongoing."
Celtic won the game against Rangers 5-1.
A Rangers spokesman said: "Rangers does not condone any form of unacceptable behaviour and the matter is now in the hands of Police Scotland."
Asked about the incident of a man allegedly running on to the pitch, Celtic boss Brendan Rodgers said: "I haven't seen it again, there was so much more happening in the game.
"It's not nice when something like that happens but I only caught the tail end of it, really."