Object necessary for warmstarting database cannot be altered ORACLE

Question

I have this error when I want to rebuild system index :

00701. 00000 -  "object necessary for warmstarting database cannot be altered"
*Cause:    Attempt to alter or drop a database object (table, cluster, or
           index) which are needed for warmstarting the database.
*Action:   None.

the command for rebuild :

ALTER INDEX I_IND1 REBUILD ONLINE TABLESPACE SYSTEM;

I tried also :

alter index  I_IND1 rebuild;

but the same message. Please any help .