Gonzalo Higuain scored the only goal of the game as the South Americans booked their spot in the last four of the tournament.
"They played an excellent match and I am extremely happy because of the boys," ESPN quotes Sabella as saying.
"After 24 years, we can be among the four best teams in the world. So as you can tell, this is a huge, but moderate joy. We have to reserve our energy."
Argentina will face the Netherlands in the semi-finals of the tournament after Louis van Gaal's side beat Costa Rica in a penalty shootout.