The young Dutchman is already under contract for next year, but after retiring in Montreal he insisted 2017 has been "completely crap" so far.
Team boss Christian Horner excused the 19-year-old, though.
"He knows how hard the team is pushing to make the car better. He'll see the big picture," the Briton said.
But Verstappen said his concerns are not just about 2017, particularly following the latest news from engine partner Renault.
"We wanted to go for the world title this year, but we are far from it," he told the Dutch broadcaster Ziggo Sport Totaal.
Renault has now said the power unit will not be significantly updated for the rest of the year, and Verstappen admitted: "I'm worried, also for the direction for next year.
"I want to win and I absolutely think this team can. You can see we have improved the car a lot. But the power is yet to come.
"And right now, as you may have read, there will be nothing more (in 2017). Updates were promised but there have been few," he added.
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