They were also found guilty by Europe's governing body of throwing objects, though it's not known whether this was during confrontations with Swedish police.
A Uefa statement read: "Setting off of fireworks - Art.16 (2) of the UEFA Disciplinary Regulations (DR).
"Throwing of objects - Art.16 (2) DR.
"The Control, Ethics, Disciplinary Body has decided to fine Celtic FC €12,500."
AIK were given a fine themselves of roughly £7,000 over blocked stairways.