Detect Collision when moving an object

Hi everyone! I'm doing some tests in Unity and last day I made an obstacle that can be movable with the mouse wheel. But when the player collides with in, the obstacle can be movable anyway. Here's a video

And here is the script that I use for move the obstacle with mouse wheel:

 #pragma strict
     var targetAngle = 0;
     var degreesPerClick = 2;
     var secsPerClick = 0.3;
    
     private var curAngle = 0f;
     private var startAngle=0f;
     private var startTime=0f;
     
     function OnMouseOver () {
         var clicks = Mathf.Round(Input.GetAxis("MouseWheel") * 100);
         if (clicks != 0) {
             targetAngle += clicks * degreesPerClick;
             startAngle = curAngle;
             startTime = Time.time;
                         }
                            
         var t = (Time.time - startTime) / secsPerClick;
         if (t <= 1) {
             curAngle = Mathf.Lerp(startAngle, targetAngle, t);
             transform.eulerAngles.z = curAngle;
         }
            
  
     }

Thanks and sorry for my bad English :P