The £20.4million German midfielder, 25, was puzzled as he made his debut in Wednesday's 4-0 destruction of Borussia Monchengladbach.
For yet again the Eithad fans booed the Champions League anthem as they continued their hate campaign against Uefa.
The attendance figure was only 30,270 — with almost 1,000 of those away fans — although the gate was not helped by a 24-hour rain delay.
Gundogan said: “The Champions League is one of the biggest club stages you can reach and I think for players it is an honour to be part of it.
“Certainly for me. You just enjoy being a part of it playing against the best clubs in Europe.
“All supporters who come along should enjoy it, too.
“I agree with the manager. The fans can always be the extra man, but in the end it is all about what happens on the pitch.
“Certainly against Barcelona, who we have in the group, it helps."