if you really need block any select... only way is execute a revoke select on <table> from <user> ... (to all users)
This is not a nice solution... but works...
Or, do the inverse. by default keep the table without select permission and create a ROLE (create role / grant role) with select permission on the table, then, when you realy need execute a select just active the role : SET ROLE <xyz>
If you use IDS 11.10 , read about LBAC, this not do exactly the perferct solution for what you need, but you can make more adaptive to you needs....