Poroshenko met Bishop as part of his visit to the United States.
According to the Ukrainian leader's press service, Poroshenko and Bishop "expressed a common position that terrorist acts cannot stay unpunished."
Flight MH17 was shot down on July 17, 2014, over eastern Ukraine en route from Amsterdam to Kuala Lumpur, leaving no survivors among 298 people on board. Local militia and Ukrainian government forces active in the region at the time traded blame for the incident.
In a separate probe into the crash, Russian arms manufacturer Almaz-Antey said the missile had exploded near the left side of the aircraft. Almaz-Antey considered this to be proof that the projectile could only be a missile from a Buk system launched from the region of Zaroshchenske, controlled by the Kiev forces at the time of the incident.