Trossard has opted out of the friendly matches against World Cup co-hosts United States in Atlanta on Saturday and Mexico in Chicago on March 31.
The Arsenal forward has only recently recovered from a hip injury, and in consultation with his club, it was decided not to call him up so that he can continue his rehabilitation in London, the Belgian football association said on Monday.
Club Brugge captain Vanaken is still recovering from a hip injury and also sits out the two World Cup warm-up games.