Verstappen has struggled with the car's bouncing in all three practice sessions this weekend, unable to match his rivals' pace.
Despite this, the Dutchman finished second in FP3 behind the Ferrari of Charles Leclerc, who has looked unstoppable thus far in Monaco.
However, the stewards let the world champion off with a warning for the incident.
Following an investigation they reported: "The Stewards heard from Verstappen, a team representative and reviewed video, team radio and in-car video evidence and determined that Car 1 was on a fast lap and had to abort the lap due to traffic at Turn 17.
"He was then told to take the chequered flag by the team. There remained some time between the instruction and the chequered flag. He said that he also saw on the TV screens that there were 20 seconds left till the end of the session.
"He then proceeded to move off the racing line at the exit of Turn 19 and stayed to the extreme left, well off the racing line till he took the chequered flag for the session.
"While doing so, he travelled extremely slowly, at times at speeds as slow as 20 kph.
"While what he did was not dangerous and did not impede other drivers, he was driving unnecessarily slowly on the start finish straight and that is a breach of Article 33.4 of the FIA Formula One Sporting Regulations. We therefore issue a warning to the driver of Car 1 for this breach."
However, the British driver had a difficult FP3, destroying his tyres following a lock-up which meant he had limited time to prepare for qualifying.
The champion managed to make it back out onto the track, and set the third fastest time of the session behind Verstappen.
Despite finishing in the top three in the final practice, Verstappen seemed unhappy with his race engineer Gianpiero Lambiase shaking his head at the end.