City currently lie in second place in the Premier League, seven points behind league leaders Manchester United, after losing 1-0 to Sunderland on Boxing Day.
But shot-stopper Hart believes the club are still on the right track and know exactly what it takes to re-ignite their wavering campaign.
“We weren’t lacking in effort at Sunderland,” Hart told Manchester City’s official website.
“We gave it everything but couldn’t break through a defensive wall. No-one else needs to know what gets said in the dressing room, it’s down to us to put things right.
|18/1||Manchester City are 18/1 to beat Norwich 4-0 with Bet365|
Meanwhile, upon being informed that Wednesday’s loss was the first time he had tasted defeat in 12 matches when paired with Carlos Tevez, Argentine forward Aguero insisted his main focus was defending City’s “hard-earned title".
“I didn't know about that statistic,” he said. “Those are good numbers, aren't they? I hope each time we play together we can keep that average. But it is not about Carlos and me.
“Beyond who is on the field, the important part is that we all work together for the same goal, because what we all want is to defend City's hard-earned title. For that we need everyone playing well and to start winning again straight away.
“Our game at Sunderland wasn’t great but we didn’t deserve to lose. We have to keep working to get ourselves back to our best form and keep our ambitions in sight.”
Aguero also dismissed concerns that fatigue is catching up with the Manchester City squad, although he did admit it felt “unusual” for him to have such a busy Christmas schedule.
“There are no worries on that score,” he added.
“It's unusual to play so many matches in quick succession; in Spain there's a brief recess at this time. But, each country has its own traditions and it’s just a matter of getting used to it.”