The Africans are in need of the points after losing their opening match 2-1 to the USA.
While admitting that Ghana will find it difficult against Germany in Fortaleza, Ayew thinks that they are capable of giving the three-time champions a hard-fought encounter.
"They're one of the best in the world, but I believe in ourselves, I believe in the squad," he told FIFA.com.
"There have been a lot of surprises in this tournament. I don't mean we're going to surprise Germany – maybe, maybe not - but one thing's for sure: we're going to give everything we have to finish the game with a positive result."
Ayew has scored five goals in 50 appearances for the Ghana national team.