Try using the word "Length" (i.e. length of polylines, perimeter of polygons) instead of "Perimeter":

    arcpy.CalculateField_management("Iceberg","Area","!shape.geodesicLength@KILOMETERS!","PYTHON_9.3","#")

I found the `geodesicLength` property documented in the [Calculate Fields examples][1] page:

> Geodesic area and length can also be calculated using geodesicArea and
> geodesicLength properties with @ followed by a unit of measure
> keyword.

  [1]: http://resources.arcgis.com/en/help/main/10.2/index.html#//00170000004s000000