Grant CREATETAB on database and then USE OF TABLESPACE only for the tablespace ..
For eg, if you want user TEST1 to create tables in TEST1_TS, then
revoke createtab on database from public
revoke use of tablespace test1_ts from public
grant createtab on database to user test1
grant use of tablespace test1_ts to user test1_ts
HTH
Sathyaram