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."
- Sports & Recreation