The 25-year-old denied the Chelsea midfielder with the scores level at the Etihad Stadium, a moment which proved decisive as the hosts went on to earn a 2-0 victory
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. "I needed to save it, the job got done and then the boys did the rest."
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."