The Albicelesti came through the group stages unscathed, picking up wins against Bosnia-Herzegovina, Iran and Nigeria to book their place in the Last 16 of the competition.
"We should be happy with our results so far,” Zabaleta told FIFA.com.
“It’s not easy to take nine points from three games at the World Cup.
"What’s most important, though, is that we’re improving as the tournament progresses.
“Against Nigeria we played better than we had in the previous two games, which was our objective,” the 29-year-old continued, before adding, “From now on the slightest mistake can send you home.”
Despite some questions being raised about the South American’s defence in comparison to their star-studded attack, Zabaleta insisted the backline are doing their job, in accordance with the team’s set-up.
"I think we’ve been playing well," said the Manchester City defender. "Because of our style of play, we sometimes leave a lot of space for our opponents to exploit on the counter-attack, which is never easy for a defender.
“But that’s our philosophy, and we’ve had two years of good results playing this way.”
Yet Zabaleta knows his team will have to be at their best now that they have reached the knockout stages of the tournament.
“We have to stay focused," he said.
"There are no easy games at the World Cup. Just look at the teams that have been knocked out, and those that are still in the race.
“Everyone wants to get to the final. I hope we can take our first step against Switzerland.”
Kick-off for the Argentina-Switzerland clash is scheduled for 6pm South African time.