The Foxes were 2-0 down through Chelsea goals from Nicolas Jackson and Enzo Fernandez before Jordan Ayew converted an injury-time penalty for the hosts.
Cooper later said: "We’ve had some terrible luck with this referee. That’s continued today. There’s also the game to talk about. Tough first half in terms of Chelsea territory and dominance with the ball. We gave away a poor goal. It should have been 0-0. We had two good chances ourselves in the first half.
"Defensively we were generally OK. We need to be showing good courage and belief. If we do that we can create chances and be a threat. We’ll always be disappointed with the goals we conceded.
"The big moment is the first penalty (not given), it’s clear what happened there. The second one was offside and you see how onside he was. That was the story of the officials’ game.
"You can (speak to them) after 30 minutes. I’m not sure if I will or won’t."