City are six points behind Brendan Rodgers' league leaders with a game in hand after beating West Bromwich Albion 3-1 on Monday night to keep their hopes alive.
They need Liverpool to slip up to stand any chance of becoming champions, but the Reds face second-placed Chelsea at Anfield on Sunday and a home defeat would leave City back in control of their own destiny.
And Zabaleta knows that City have to keep the pressure on by winning all their remaining games, starting with this weekend's trip to Selhurst Park to play in-form Crystal Palace.
"We still have four games to go until the end," said Zabaleta.
"It's going to be tough, but we need to keep believing. We know in football that anything can happen.
"We have put pressure on Liverpool. We now need to wait for Liverpool to drop some points, which they can do in some games.
"We must move on to the next game and get three points at Crystal Palace.
"Nothing is over. In football, you know anything can happen.
"The most important thing is to keep working hard, keep doing everything possible until the end and then we will see."