The 26-year-old accused his team-mates of taking their "foot off the gas" in a second period that saw Spurs score three goals in seven minutes.
Frenchman Samir Nasri had put Roberto Mancini's men ahead in the early stages, and after the match Hart rued his side's inability to kill off the game.
"We took the lead and didn't kick on from there. Second half we just kind of existed and paid the price," Hart told City TV.
"I just thought we took our foot off the gas and you can't do that. Spurs have got a lot to play for and congratulations to them but I'm not really interested in them.
"We messed up in Europe and we have had plenty of weeks rest so I don't think that is what it is down to. It was just a poor second half."
However, the England international has now urged his team-mates to move on and focus on Saturday's clash against West Ham before they face Wigan in the FA Cup final.
"We will bounce back easily, it is what we do," he added. "We have proved that many a time. We have a big game coming up against West Ham.
"It is always good to win at home and we have got the FA Cup final that all the boys are trying to win their spots for."