Mascherano had a difficult debut in Barca's shock defeat to Hercules on Saturday.
But he said: "I'm not worried, but I have to be careful not to get carded after 20 minutes because that affects you for the rest of the game.
"I have to adapt, because I've spent a long time in a much more permissive league in terms of physical contact, and sometimes you forget that when challenging for the ball and so I need to put a stop to that.
"But I want to make it clear that it was not an attack on referees here, it's just that football's different here.
"He [Guardiola] wants me to play the ball a lot more, because unlike in English football, defensive midfielders here play their part in taking the ball forward. He's always telling me about positioning and making myself available, and where to be when we're putting pressure on the opposition.
"But it isn't really all that different to what I have always done. It's more or less the same, just that you play a bigger role on constructing moves."