The reigning Premier League champions were tipped to do well in the Champions League this campaign but ended up finishing at the bottom of Group D following tonight's 1-0 loss at Borussia Dortmund.
A win would have seen City slot into third place ahead of Ajax to grab a Europa League spot but they could not even muster that and Hart is looking for a positive response before coming back a better side in Europe's premier club competition next term.
"We have let ourselves down. We need to be winning," said Hart, who copped 11 goals in six group stage matches
"I think Borussia and Real Madrid have done fantastic but we should be fighting till the last day to be in the competition and we weren't.
"We should have been in their position and we weren't. We've only got ourselves to blame.
"We've been disappointing in Europe but we've been fantastic in the league and consistent.
"So I don't think there are any worries about that but we need to address it to get in that Champions League again. Hopefully we can win the league then we'll be able to deal with it next year."