The Spain Under-21 goalkeeper wants to see his international teammate make the move to Old Trafford this summer, although he has acknowledged a transfer could be problematic.
The Premier League giant is keen to add some fresh blood to the midfield this summer and has reportedly made Thiago one of its primary targets on the transfer market.
"Hopefully I will have a Spanish teammate at United next season. I, and every other Manchester United player, would like him to join the club," De Gea told El Mundo Deportivo. "We have been joking about him joining United. Barcelona will realize that they have a great player, though, and I don't think they will let him go."
The Spain international has a contract with Barcelona until the summer of 2015, but the failure to participate for a stipulated amount of minutes in 2012-13 has seen his exit clause plummet from 90 million euros to a more attractive 18 million; however, his minimum fee release clause returns to 90 million on Aug. 1.
Thiago, whose hat trick in the Under-21 European championship final helped Spain to a 4-2 victory over Italy, is a product of the Barcelona youth academy and has made more than 100 official appearances for the Catalans since making his first team debut in 2008-09.