However, Mourinho is confident that the players' experiences at club level will help them through the tournament, and tipped them as outsiders to pip the likes of Germany, France, Spain and Brazil to the trophy.
"They have a good group of young but experienced players," Mourinho is quoted as saying by Sky Sports News.
"All of them play in the most competitive competition in the world, the Premier League, all of them playing for the best teams with experience of playing in the Champions League, which is a high level of football, obviously. Yes, I think they can do it.
"[The favourites] have good squads but good squads don't always make good teams. Sometimes not such good squads, in theory, can make better teams...[but] I don't think the underdogs will make a big surprise. In the end, the top teams in South America and Europe are the ones that will be fighting for the title."
England will begin their campaign against Tunisia in Volgograd on Monday before taking on Panama and Belgium in their final two group games.