"I think we are still quick," Verstappen said to RaceFans on Red Bull, who were victorious in Monaco last season. "In the second practice, when everybody went onto their second set, we had a radiator leak because some debris flew into the airbox and damaged one of the radiators so we had to replace it. In general, it's alright."
Mercedes topped both sessions on Thursday, with the Silver Arrows finishing seven-tenths ahead of Sebastian Vettel in FP2 - who was the next fastest car.
"I think Mercedes is too quick," Verstappen continued. "But the big gap in between second and third, we should fill that up."
Verstappen returned to the track towards the conclusion of FP2, but was then heard complaining about the car's balance. The 21-year-old explained what exactly happened in a bit more detail: "It didn't work but I know that if we go back to the other set-up, it's not too bad.
"The balance is OK. They only broadcast, of course, the negative things at the end. But in general, it was alright. Of course you try different things in practice. Some work, some don't, so it's alright."