The 23-year-old sustained a small muscle tear in Real Madrid's 1-1 derby draw with Atletico Madrid on Sunday, the Spanish Football Federation (RFEF) announced on their official website on Tuesday.
Spain coach Luis Aragones has called up Sevilla midfielder Antonio Puerta as a replacement for Reyes, who is currently on loan at Real from English giants Arsenal.
Reyes will also miss his country's friendly game against Argentina on the 11th of October.
Under the guidance of Italian coach Fabio Capello, the former Sevilla man has enjoyed a fine campaign so far with Real.
He netted two goals in the Spanish La Liga and the UEFA Champions League as well as providing many assists to his teammates.
Spain are in second place of Group F With three points, three behind leaders Sweden after suffering a surprising 3-2 away defeat to Northern Ireland last month.