Van Gaal told reporters on Tuesday that Huntelaar was bothered by an eye injury and had left the training camp.
"The call for Robben is an exception through the injury of Huntelaar," Van Gaal said.
"I needed a top class striker and that is why I added Robben."
Van Gaal left Robben out of his original squad because he is not playing regularly for his club Bayern Munich.
The coach named the following team to start against Italy in Amsterdam, with Manchester United's Robin van Persie leading the attack.
Netherlands: Tim Krul; Darryl Janmaat, Stefan de Vrij, Bruno Martins Indi, Daley Blind; Kevin Strootman, Adam Maher, Jordy Clasie; Jeremain Lens, Robin van Persie, Ola John.