Harry Maguire is shown a “lack of respect” by the media, according to Crystal Palace manager Patrick Vieira.
The 29-year-old centre-back has made just nine appearances for United this season.
“Maguire is a top player who has a really strong character,” said Vieira.
“Sometimes you can play well and sometimes you can play badly, but that doesn’t take away the quality that he has and the personality that he has.
“The England national team will benefit from that.”
He added: “I think sometimes you guys [the media] show a lack of respect to Maguire and to some of the players who have been selected in the national team.”
Crystal Palace defender Marc Guehi, who made his England debut in a 2-1 win against Switzerland at Wembley in March, missed out on a place in Southgate’s squad.
“Regarding Marc, what he had to do is to keep being consistent with his performances,” said Vieira.
“Marc, if you compare him to Maguire, [the difference is] Maguire knows [things] at international level which Marc doesn’t know yet.
“The manager has to make a decision about what he wants for that tournament. Again, Marc, or anybody else, should respect that decision and make a judgement at the end of the tournament.
“The manager knows the player better than we do. The manager knows what he wants from players and how he wants to play the game.
“The nation has to trust, believe, and be behind the manager. Then, when the tournament is finished, everybody can express their opinion.
“I believe that what England needs is for the opinion of the nation to be behind and to support the decision of the manager. Then, see how is goes.”