There is the SQL*Developer migration workbench but his currently does not support the migration from Postgres to Oracle.
I think your only option is to find a third party tool that may be able to help.
There are some links to third party partners and support from the the following -
Oracle Database Migration Technology
under the heading -
Finding More Help: Oracle Migration Partners and Support
You could also have a look at this note in My Oracle Support which has some other ideas -
How To Migrate Non-Oracle Databases For Which A Migration Workbench Option Is Not Available (Doc ID 393760.1)