what is the official ruling

[charleshaddon81]

So in an 18 under AAU basketball game, the guard is being heavily defended by a taller player. He gives a pump fake to the defender and drives left towards the basket. The defender gets back into position but his hands are on the players hips. It does not look like he changed the momentum of the gaurd dribbling the ball, but none the less, I heard it from 2 coaches that the any time the defender places his hands on the hips of the man dribbling the basketball it is a foul. I thought as long as the players momentum was not impeaded that it was not a foul, or is any touching to the hips, whether it slows momentum down or not a foul?

Thanks.