Ward was set to be part of manager Michael O'Neill's squad for the friendly against Malta in Valletta on Wednesday.
But the 26-year-old, who scored for the Rams on Saturday in their 3-0 win over Huddersfield at Pride Park, was replaced during the latter stages of the game after feeling some tightness in his hamstring.
Ward has only recently returned to action after being out for more than three months with hamstring trouble.
He will remain with Derby to receive treatment and is expected to be fit for their npower Championship clash at Sheffield Wednesday at the weekend.
Ward, capped for times by Northern Ireland, has been replaced in the squad by former Derby trainee Gerard Doherty. The Derry City goalkeeper is uncapped.