Wednesday's defeat to Ajax has made qualification unlikely for City but Lescott believes that their main concern should be the match with Swansea City on Saturday.
The England international said: "It's hard to put your finger on why it isn't working in Europe but we can't let it affect our league form.
"We haven't done so far and we won't do on Saturday. Swansea will be a very different game. We're at home so we'll look to dictate that game and create some more chances."
The champions have yet to lose a game in the league this season.