That is definitely a message indicating that autocommit is ON. No other circumstance would produce that message.
If you were running this in SQL*Plus or SQL Command Line, then the “show all” command (or “show autocommit”) suggested by Rechil will show you the autcommit status, but issuing a commit in a SQL*Plus or SQL Command Line session does not produce any error, regardless the autocommit setting.
If you are running this from the web interface (SQL Workshop or similar) then there must be an “Autocommit” checkbox that is currently checked. You need to look for that option and uncheck it. There is no other solution (apart from running your commands in SQL Command Line or some other tool).