Celtic have been hit with a €12,000 fine after fans pyro display against Cluj earlier this month.
The flares were part of the display in the standing section of the ground ahead of the Europa League tie, which Celtic won 2-0.
The slap on the wrist is the latest in a series of fines from UEFA, with the club in the dock 17 times over the past 12 years.
Celtic had release a strongly worded statement after the latest charges and suggested they would be cracking down.
They said in a statement “Celtic will be introducing further measures in order to deal with this behaviour. It has to stop.”
The club had hinted at “hugely detrimental consequences” should warning continue to be ignored.
Their statement on the official site continued: “Given the number of repeated offences, we should also be very aware that there could be further, very serious repercussions which could have hugely detrimental consequences for the Club and our supporters.
“It is hugely unfair that the enjoyment of Celtic matches could potentially be affected by the negative behaviour of a tiny minority.”