Speaking ahead of the UN Climate Change Conference COP26, the heir-to-the British throne, 72, who has spent most of his life speaking out on green issues, said he understood why campaigners took direct action when faced with the inactivity of politicians.
"They just talk," Charles told BBC TV in an interview broadcast on Monday. "And the problem is to get action on the ground."
His views echo remarks from Thunberg and her fellow youth campaigners at a Youth4Climate event in Italy last month when she accused world leaders of "thirty years of blah, blah, blah".
Charles said he understood young people's despair and why groups such as Extinction Rebellion took to the streets to carry out disruptive protests.
"All these young feeling nothing is ever happening, so of course they're going to get frustrated. But it isn't helpful, I don't think, to do it in a way that alienates people," Charles said.
Charles, who will be joined by his mother Queen Elizabeth and his eldest son Prince William for events at the COP26 summit, has been calling for governments to work with business chiefs and the private sector to help solve the climate crisis.
Asked if the British government was doing enough, he said: "I couldn't possibly comment."
However, he said the Glasgow COP26 summit, which runs from Oct. 31 to Nov. 12, was a "last chance saloon". Without action "it will be a disaster", he said. "It will be catastrophic. It is already beginning to be catastrophic."
Questioned about his own green credentials, given his passion for cars and the carbon impact of royal palaces, Charles said he had converted his 51-year-old Aston Martin to run on surplus white wine and whey from making cheese, and had installed biomass boiler systems and solar panels at his homes.
He also said he did not eat meat or fish two days a week, and had no dairy products on Mondays.