Alejandro Sabella's men qualified for the last 16 in Brazil after finishing top of Group F with maximum points.
However, Argentina showed defensive frailties in the 3-2 victory over Nigeria, while the South American side also looked vulnerable at the back in the 1-0 triumph against Iran.
Switzerland provide the next test in the round of 16 and Manchester City full-back Zabaleta is well aware Argentina must be more balanced in their play and can ill-afford mistakes.
"Beyond having qualified first, we know that there is always room for improvement and can work to adjust," he said.
"We are entering a decisive phase in which there is no margin for error.
"I think the important thing was learning about how rivals may pose (threats) in matches and how important it is to be more cautious about some things, and braver in other (situations).
"Now the situation is different because each stage is crucial. We hope our rivals are more open and we can take advantage of these spaces. The important thing is to keep the balance."
