Create a directive that excludes named folders

We use netapp to snapmirror data to our HQ site from a remote site.  This snap mirrored folders are read only and every folder recursively contains a .snapshot folder.  Since it is read only I cannot write in any nsr.dir files to these directories.  

Does anyone know if directives has the ability to exclude all folders with a specific name?  What I am getting from directives is that you can specify a directory and exclude files recursively but it is not apparent that you can specify a directory name pattern instead of a file name pattern under that directory.