The England No.1 brought Demba Ba to ground in the box with the scores tied at 0-0 after 52 minutes, but atoned for his error by producing a fine stop to deny Lampard.
And, after strikes from Yaya Toure and Sergio Aguero handed City victory, Hart explained that he was desperate to keep the spot-kick out.
He told the club's official website: “I needed to do it [because] I obviously gave the penalty away. Demba Ba was clever and left his knee in.
|20/1||Manchester City are 20/1 to win the Premier League with Bet365|
The 25-year-old also revealed that he has previously discussed penalties with England team-mate Lampard and revealed his admiration for the Blues midfielder.
“We talk about it [penalties] at length,” he added. “I enjoy talking to him about football, he's a hero of mine, and a really tough opponent.
"I'd stay behind for hours, if I could, practising penalties with him because I know how good he is. I don't think I'm ever going to affect him, I think he's got his way to do it and luckily I went the right way."
And Hart went on to say that he still holds hope of catching Manchester United at the top of the Premier League, despite the 12-point gap between the teams.
"We never give up, I think we've made that obvious. Even if there's one game to go and there's still 12 points we'll do everything we can to win the league - even if it's not possible!
“Obviously United, if they keep on winning, there's nothing we can do but if they don't, they need to know we're going to be there."