Europe's ruling body confirmed that the Scottish Champions have to answer a charge which allegedly breaches articles 16.2 of UEFA's disciplinary regulations.
The Hoops won 2-0 against the Irish part-timers to go through to the third qualifier against Swedish side Elfsborg on a 5-0 aggregate with the first leg at Celtic Park next Wednesday night.
Celtic were been fined 25,000 euros (approx £21,000) for fans' misbehaviour in the Europa League game against Udinese in Italy in December, 2011.
After the 1-1 draw at the Stadio Friuli, the Parkhead club were charged with, "the displaying of a banner of an offensive nature and the setting off of fireworks by supporters".
In a statement, Celtic admitted the fireworks were used in a section of the stadium housing the Green Brigade supporters group, causing the referee to ask the club's safety officers to intervene.
The club said: "Three fireworks were exploded within Section 111, causing the Match Referee to require a stadium announcement to be made instructing such behaviour to stop.
"As a result of this unprecedented step by a match official, Celtic FC will now be the subject of a disciplinary action for contravention of the UEFA Safety and Security Regulations."
Article 16.2 decrees that "all associations and clubs are liable for....inappropriate behaviour on the part of their supporters and may be subject to disciplinary measures and directives even if they can prove the absence of any negligence in relation to the organisation of the match" relating to, among other things, the "lighting of fireworks or any other objects".
- Sports & Recreation