Straight from nba.com
While some contact may occur during a game, it does not mean a foul has been committed. Contact which is incidental to an effort by a player to play an opponent or to perform normal defensive or offensive movements should not be considered illegal. Players are allowed normal body contact with opponents when reaching for a loose ball if they both have the same opportunity to get the ball. This type of play shall be ruled incidental if neither illegally gains an advantage. The hand is considered “Part of the ball” when it is in contact with the ball. It is not a foul if a defensive player makes normal contact with a players hand when it is in contact with the ball.