SQL & PL/SQL

I need to drop an index from a table that is constantly used , read and write.
The DML's are locking the table and preventing the index drop (ORA-00054: resource busy and acquire with NOWAIT specified )

I tried to lock the table first - using 'lock table TAB1 in exclusive mode'
but when i ran the 'drop index' command , the drop (as all DDL's) first commits and this frees the lock which cause again the ORA-00054: resource busy and acquire with NOWAIT specified error.


I would appriciate any help .I can't take the DB or table or Application writing to the table offline. I need something like 'create index IND1 online' for DROP but there is none as far as I know...

Thanks in advanve.
Amit Zor