City's attendances in Europe have been disappointing in recent years, with many fans opting to boycott European fixtures over what they perceive as unfair treatment by UEFA dating back to 2011/12.
The Premier League champions are currently being investigated regarding suspected Financial Fair Play breaches and speaking ahead of Wednesday's game, Walker admitted that there is a noticeably different atmosphere at the Etihad to other ground.
"I'm too [busy] concentrating on my game than worrying about the fans, but obviously you do want an atmosphere," Walker insisted.
"When you go to certain grounds, it's difficult to play there sometimes when you've got the atmosphere and the fans are on their side, so we do probably like that a little bit.
"We've come to terms with that and we have to just let our football do the talking. We've got some fantastic players in there and our fans probably shouldn't influence us on how we're going to play throughout the 90 minutes."
The England international then followed up by calling for City's fans to be the 12th man at home and in Europe.
"Obviously the Manchester City fans have their opinion on the Champions League which is what it is, but for us it's down to us as players to create the atmosphere in there and help the fans as well - they're the 12th man," Walker said.
"We have an important job on the field to get the victory. We need to make history for this club and that's what we're wanting to do."