How to move on PhysicsConstraint without shake?

I use an add impulse on a box to move it along a PhysicsConstraint, in order to push the player away from a wall (the box is a child of the player), but when the player is moving towards a wall and I push the box with add impulse, the box shakes as it tries to push the player and wall apart.

is there a way to stop this shake? or another way to move the box along the PhysicsConstraint, without relying on physics?