The 47-year-old told The Express: "We certainly shouldn't be leaving here on the end of a 1-0 scoreline. We have hit the woodwork and had numerous chances in the second half.
"In our first foray in European football, I think that this was an outstanding performance - we looked like a very mature European team and I was delighted with them.
"My only disappointment is to leave with no points, because we certainly deserved to take something from the game."
Despite the defeat, Wigan remain in second place in Group D, above Zulte Waregem and Maribor.