The 29-year-old was on the shoulder of French leader Renelle Lamote coming off the final bend but was overtaken by Rose Mary Almanza of Cuba and Rababe Arafi of Morocco to finish fourth.
Sharp's time of two minutes 3.57 seconds was not fast enough to secure one of the fastest losers' spots.
European champion in 2012, the Scot finished sixth at the Rio de Janeiro Olympics in 2016.
World Championships
I am a clean athlete, says Hassan
05/10/2019 AT 22:27
The event is missing triple world and double Olympic champion Caster Semenya, who has challenged the IAAF’s recently-introduced testosterone regulations.
The South African lost her appeal at the Court of Arbitration of Sport (CAS) against the rules that mean middle distance female athletes with a high natural level of testosterone must take medication to reduce it.