Change Tablespace of All the Indexes

SQL>spool indexes.out
SQL> SELECT 'ALTER INDEX ' || INDEX_NAME || ' REBUILD TABLESPACE NEWTABLESPACE;' FROM USER_INDEXES;
SQL>spool off
SQL>@indexes.out
Note: Here Newtablespace refers to the tablespace where you want to move your indexes. Preferables is you should create another tablespace to keep indexes.