The race at Suzuka was suspended after just two laps due to heavy rain, which resulted in a number of incidents on the opening lap.
A crash for Carlos Sainz at Turn 12 initially prompted a safety car before the red flag was thrown, with all cars returning to the pit lane.
But before the field returned to the pits while circulating behind the safety car, a recovery vehicle was already stationary on-track at Turn 12 in order to address Sainz's car.
Gasly was the last driver to pass the tractor, and was left furious over the radio that there was a vehicle on-track while cars were still passing at speed.
The FIA stewards have now confirmed via race control that they will investigate the incident involving Gasly on lap two at Turn 12 after the race.
The stewards bulletin states this is for: "Alleged breach of Article 57.2 of the FIA Formula One Sporting Regulations – Speeding under Red Flag Conditions."
"Car 10 reached speeds of up to 250 km/h when completing the lap under the red flag after passing the scene of the incident," the bulletin adds.
The red flag was shown just as Gasly approached the stationary tractor on-track, but the stewards' statement notes the speeding relates to the remainder of the lap once he had passed the incident site.
Gasly went to see F1 race director Eduardo Freitas during the red flag stoppage about the incident. Under appendix H of the FIA's International Sporting Code: "No marshal or vehicle shall enter the circuit perimeter without permission from race control."
Under Article 15.6 of the sporting regulations, the race director "must be in radio contact with the clerk of the course and the chairman of the stewards at all times when cars are permitted to run on the track.
"Additionally, the clerk of the course must be in race control and in radio contact with all marshal's posts during these times."
