Hart, 23, has established himself as England and Manchester City number one and now Capello wants him to make his name on the world stage.
Capello said: "He has to understand when you play with your team you have to be focused every game. With Manchester United, Manchester City and Arsenal you cannot make mistakes because every game you want to win if you want to arrive at the top of the table.''
Mistakes such as the one at Leicester which forced City into an FA Cup reply have not gone unnoticed.
Capello added: "He has made mistakes, but he is young. It is important for England that he is able to remain focused in every moment of the game.
"It is difficult to play in a team that spends a lot of money and needs to win. You have to understand that when you play against other teams who are in the middle of the table or lower, this team will play against you and give 110% to beat you. For this reason he has to play every time at the top because he has to be focused only on the game.''