use the returned value of the query as a foreign key without starting a new transaction or dropping foreign key constraint

I'm inserting a value in table A, that has a serial type as primary key.

Using the returned value of the query as a foreign key of table B I get:

ERROR: insert or update on table "tb_midia_pessoa" violates foreign key constraint "tb_midia_pessoa_id_pessoa_fkey"
DETAIL: Key (id_pessoa)=(30) is not present in table "tb_pessoa"

How can I use the returned value of the query as a foreign key of table B without starting a new transaction or dropping my foreign key constraint?