After the Ticos beat Italy on Friday, FIFA ordered seven of their players to undergo post-match doping tests, while only two Italian players were tested.
In a statement posted by Football Italia, FIFA explained that two Costa Rica players were ordered for normal post-match tests, while the five others had not done pre-competition testing
Navas, Ruiz, Celso Borges, Joel Campbell, Yeltsin Tejeda, Christian Bolanos were among the players who took and passed the test, while reports said Michael Barrantes was the seventh.
Following almost two hours spent between the locker room and doping control, the last three Ticos players finally appeared after taking the test.
Goalkeeper Navas said that "people still don't believe" that Costa Rica could beat Uruguay and Italy.
"We believed it from the outset, but thank God we're all relaxed, with a clear conscience," Navas said. "If they want to test the whole team, that's no problem".
Navas said that initially it may not "have sat well with them" that so many players had to attend the doping tests, as it could be seen as a "a lack of respect as well."
"You have to take it in good humour," he said. "At the end of the day, we're all relaxed and happy that we've gone through" to the knockout stage.
Team captain Ruiz also supported the words of his teammate.
"It seems a little bit excessive to me, but we can't do anything about it," he said. "We've got nothing to hide. We have trained well, without taking any banned substances. It's partly that people can't believe what we're doing, I think that's it.
"They ordered the tests, we didn't have a problem with taking them, but perhaps seven is excessive."