Hart was criticised by City boss Roberto Mancini for his comments.
But Southgate told Absolute Radio: "I think it's great to see players as honest as that, and it's always difficult when you put a microphone under somebody's nose straight after a game. I think that just showed the emotion involved when you lose a game like that so late on.
"He's right, as a player at that stage you can't take any positives, but I think, you know, a few days further on they'll look at the game and feel that there was a lot of good things from Manchester City's point of view. They're in a very, very tough group, but they've still got a good chance to get through."
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