The Red Devils sealed their 20th top-flight crown with four games to spare this season with their 3-0 win over Aston Villa two weeks ago.
Vidic told PA:"The most important thing is to win the games and keep that winning mentality. Sometimes when you play without the pressure you can have a good game and enjoy it more.
"There is enough of a motivation for us. We are motivated every time we step out at Old Trafford. When we go into the games we have a mentality to win which is not going to change against Chelsea or anyone else.
"The only difference is we are relaxed. We are not chasing points for the trophy. We have won that so we can enjoy the game. We will try to win. We don't want to lose the last three games. We want to finish in a good style."
United face Chelsea at Old Trafford later today.