A number of fans gathered outside Celtic Park ahead of the Old Firm game and released pyrotechnics, police have said.
While no arrests were made, Police Scotland voiced disappointment that the fans had ignored advice to stay away.
The match, which Rangers won 2-0, was played in an empty stadium due to Covid-19 restrictions.
Superintendent Stevie Dolan said: “Despite there being no spectators, a policing plan was in place in case of any issues outwith the stadium.
“Disappointingly, despite the clubs, Government and police asking people to do the right thing and stay away, a minority of fans did gather near Celtic Park ahead of the match and pyrotechnics were used.
“Our approach throughout the pandemic has been to engage with the public, explain the legislation and guidance, and encourage compliance, only using enforcement as a last resort.
“We will continue with that approach, but we will not hesitate to use enforcement action where it is necessary.”