The Moroccan champion finished 4th in the first heat, setting a time of 3:36.44. Great Britain's Josh Kerr (3:35.83) won the race ahead of Kenya's Brian Komen (3:36.31) and Norway's Narve Gilje Nordas (3:36.41).
The semi-final will take place on Sunday, August 4.
Later today, Morocco's Assia Raziki will make her debut in the 800m event.