Juve had been crowned champions on Sunday, but Ronaldo was still fielded for a full 90 in the loss on Wednesday night.
Sarri insisted: “Speaking to him yesterday, he was very motivated, wanted to play, was really enthusiastic and felt good.
"We made the decision together, he knows his body better than anyone.
“Ronaldo is instinctive and doesn't fit entirely into certain tactical roles, which is also his strength, but it means the other striker has to adapt to Cristiano's movements. We did it well at times this evening too, but didn't finish the moves."