UEFA awarded the Scottish champions a default 3-0 win in the second leg of the tie after it was discovered that the Polish club, managed by Deila's fellow Norwegian Henning Berg, fielded substitute Bartosz Bereszynski near the end of the 2-0 second-leg win at Murrayfield on Wednesday night while he was supposed to be suspended.
Consequently, Celtic went through on away goals after a 4-4 draw and were drawn against Slovenian side Maribor in the Champions League play-off.
Speaking at the club's Lennoxtown training complex Deila said: "It is very strange, I have to say that.
"First of all I feel very sorry for Legia, and my friends from Norway there.
"It is tough to think of that and now we are in the Champions League.
"That is what UEFA said, we haven't been involved in anything.
"I am a football manager and I have to go with it and now we are preparing for Maribor."
Deila confirmed he had not spoken to Berg but he swerved a question about him possibly feeling embarrassed by the extraordinary circumstances in which his side were handed a reprieve.
The former Stromsgodset manager said: "Legia played well against us, they put in good performances but this is nothing to do with Celtic. It is about UEFA.
"It is not my business. It is a club thing and a UEFA thing."
The Hoops boss also claimed that it was difficult to consider UEFA's decision as another opportunity for the Parkhead side to make the group stages of the competition.
"It is very hard to think of that today because it is a tough decision and I really feel sorry for Legia," he said.
"But we have to go into the game and prepare for Maribor.
"The players want to play in the Champions League. It looks like we have been given another chance and I think it will be no problem to get the players up for the game."
Deila did concede that the continuing possibility of Champions League football could be influential in recruiting new players to Celtic and keeping those who might be thinking of leaving.
So far, only former Hearts and Sunderland keeper Craig Gordon has been signed and Jo Inge Berget has arrived on a six-month loan deal from Cardiff City, while many are expecting keeper Fraser Forster to depart, with Southampton heavily linked with the England international.
"We are working really hard now to get players in for the next stage, "said the Parkhead manager.
"Of course, there are many aspects of keeping players and getting players in but that (Champion League football) is one of those aspects.
"It is a vital thing (getting back in) It will lift the team and performance."