Edit your script and filter out/exclude the datafiles that are autoextensible to be YES.
scott@9i > select file_name,autoextensible from dba_data_files;
FILE_NAME AUT
---------------------------------------------------------------------- ---
/u01/app/oracle/oradata/mutation/system01.dbf YES
/u01/app/oracle/oradata/mutation/undotbs01.dbf YES
/u01/app/oracle/oradata/mutation/indx01.dbf YES
/u01/app/oracle/oradata/mutation/tools01.dbf YES
/u01/app/oracle/oradata/mutation/users01.dbf NO
/u01/app/oracle/oradata/mutation/test.dbf NO
/u01/app/oracle/oradata/mutation/xdb01.dbf YES
7 rows selected.