City are all but in the Wembley final of the competition after hammering the Hammers 6-0 in the first leg of their semi-final tie at the Etihad Stadium two weeks ago and play the return meeting at Upton Park tonight.
"It doesn't matter about the first leg," Zabaleta told reporters. "We have to go into that game thinking it's a new game, even though we have six goals.
"We need to try and win it, like we are doing in other games at the moment. We are winning games and working hard.
"West Ham are in a tough moment, they are at home and will want to win it. So we need to take it seriously and we will."
The match kicks off at 7.45pm tonight.