Safari generates a graphic for links (<a href="...">) when they are in the start of a drag operation. Like wise a translucent version of an image is used if it (<img src="..." />) is being dragged.
Neither of these can be overridden by event.dataTransfer.setDragImage(...);
This means that if it's really a parent element underneath a link that is going to be dragged, Safari will still display a link dragging graphic. It might be confusing since the actual drag data may not be a link at all.
It's not possible to just disable the drag image completely neither.
*** This bug has been marked as a duplicate of 24735 ***