From the popup I think you still can perform calculate geometry. As popup mentions, you are having more than 500 records on which you will be running calculate geometry. So its just a warning message that you can not use ArcGIS's undo and redo functionality for the changes made by calculate geometry.
It also says if you are in editing session while doing calculate geometry, you can undo changes by not saving the edits.
So bottom line is, you can use your calculate geometry.
I hope that is what you are looking for.