I am using Postgres for a django project and I am currently implementing a database backup/restore system that as simple as possible performs a pg_dump when the user clicks
It seems like pg_restore tries to restore some extra data which you don't own. Try to add -n public option to your pg_restore command line. It will tell pg_restore restore only contents of public schema. Your command line should looks like
pg_restore -U username -c -n public -d database_name