City thumped Sunderland 3-0.
Mignolet said: "They really wanted to win the game and played really well.
"We had some chances on the counter-attack but not enough to threaten the opposition, whereas they created a lot of opportunities.
"You always know that when you play against Manchester City you are going to be busy.
"But we want to win games and it doesn't matter if you make a save or two. You don't want to concede three. It's always disappointing.
"In games like this you want to keep it goalless as long as you can, but by conceding early it meant a tough game got even tougher.
"After going ahead early City pressed us really high up the pitch and created lots of chances."