"I already said before the Fiorentina game that we certainly didn't like playing three games in seven days," said Conte.
The Bianconeri beat Celtic 3-0 in the Champions League on Tuesday evening.
"We were bound to pay for that with fatigue and one more day would've helped us to rest and reorganise. This is the only excuse I can give for today, as we did not play as a team and when we do that anyone can beat us.
"We have regrets that there was not one more day to prepare and recover our fitness levels. I hope in future when the fixture lists are drawn up there can be a little more respect for a club that is taking Italy forward in Europe."