The north London club are currently five points behind the league leaders in third place, as they prepare to take them on in a game at Eastlands on Sunday.
The last time these two sides met in the league proved to be a difficult occasion for Spurs, as they fell to a heavy 5-1 defeat at White Hart Lane.
Now, the Dutchman believes that any hopes the north London club have in the title race are on the line when they take on Roberto Mancini's men.
"We have to win to keep the league a bit closer," said Van der Vaart, according to The Mail on Sunday.
"I don't think we can play for a draw. Everything depends on this game. If we can win there, everything is really open. Of course if you lose, it's eight points and that's a lot."
The former Real Madrid man also suggested that City might be prone to underestimating Spurs because of their previous result against them in the Premier League.
"I think maybe still in their head is the 5-1," Van der Vaart said. "We were trying at the time to sign Scott Parker and Emmanuel Adebayor. That's not an excuse to lose 5-1, but it was one of the reasons.
"We are a different team now, much stronger. After the game, we can see where we stand. We have to respect City because I think they have maybe the best squad in the league, certainly the biggest.
"They spend a lot of money and they can do it so let's hope we get a good result. We are much more consistent now: last year we dropped too many points against smaller teams."
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