You definitely can just take extra care when moving it around. Cast iron can scratch the top if it is moving a lot. Make sure you clean the surface immediately after cooking as cast iron reside can leave marks on the glass top if left to sit too long after cooling down. I would suggest heating the pan at the same time as the top, meaning turning the burner on with the pan in place. Many of my customers love to cook with cast iron and have done so on glass tops for many years with no problems.