The Valencia winger was part of the side that secured a 2-1 win over Japan on Saturday, but defeats to Italy and Brazil had already eliminated them from the competition.
"We improved for this match [against Japan] but I'm sure that we can do better than that. We have a lot of work ahead of us if we want to qualify for World Cup 2014 in Brazil," he told reporters at a press conference.
"The qualifiers are still our priority and we will focus on that soon but it's true that this victory was a boost to our confidence and we plan to build on that to improve in the following matches.
"We are always proud to play for Mexico and we don't feel good when results don't go our way but this time it was different and we can be happy about that but not about our overall performance. We would have liked to qualify."
Guardado has made 97 appearances for his country.