But despite bringing on Pedro and Willian and having an extra man advantage, the champions failed to break down a resolute Leicester who were solid in defending.
"I know we as a team didn't have a good game", the goalkeeper said to the club's official channel, Chelsea TV.
Courtois, 25, said to Sky Sports after the game: "It doesn't help when the fans boo and whistle after each misplaced pass".
"In the first half Leicester ran more than us, they played better than us".
Conte said: "I saw many players exhausted, but don't forget we played a massive game on Wednesday night against Arsenal and then I chose to pick the same formation after two-and-a-half days, and maybe I made a mistake because many players didn't recover from this effort".
It was a torrid affair for the home side, with Eden Hazard being substituted for the fourth game in a row and Gary Cahill going off with a hamstring injury.
Chelsea have registered three consecutive goalless draws in all competitions for their first time in their history.
The result represented the third goalless stalemate in the space of a week for the Blues, who were held both by Arsenal in the semi-finals of the EFL Cup in midweek and by Championship side Norwich City in the FA Cup last weekend.
The 48-year-old said: "I saw a lot of players that looked exhausted". Very exhausted. I think we played with tiredness.
"Obviously they knew we've had a lot of games and they started very aggressive with a lot of intensity".
We did this. In the FA Cup we played with one team, in the Carabao Cup we played another team, and today we played nearly the same team as Wednesday.
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