Water dispenser and water hammer / vibration

The water dispenser is working on our refrigerator but when doing so there is a loud juddering coming from the rear of the fridge. If i look around the rear of the machine the water pipe into the fridge is shaking around / vibrating when this happens . It stops immediately when you stop drawing water from the dispenser. The pipe does not vibrate and there is NO juddering when the ice maker fills and water is flowing to that device