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 method documented in the Calculate Fields examples page:

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

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 page:

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