Tevez has scored three league goals in five games since joining the Italian champions from Manchester City in the summer.
"I was genuinely surprised," he told Tuttosport. "I thought it was easier to play here, but instead it is more tactical, fast and a lot more hard work. It is the most difficult League in which I have played.
"It seems that every team who comes up against Juventus treats it like a World Cup final. Everyone wants to beat us – so we always have to give 100%. It's incredibly difficult."
Tevez has been capped 62 times by Argentina.