Her arrival in the UK comes as Extinction Rebellion activists took over part of the Natural History Museum on Monday and marched on Parliament on Tuesday morning.
More than 1,000 people have been arrested since their protests began in central London a week ago.
Speaking in the House of Commons, energy minister Claire Perry said she had "mixed emotions" about the protests, which had raised important issues but risked leaving people "fearful for the future rather than hopeful".
Miss Thunberg, who spoke to the crowds in Marble Arch on Sunday, told the BBC that disruptive action "definitely has a lot of impact".
Asked whether it was necessary, she said: "As long as it's non-violent, I think that could definitely make a difference."
'No point in anything'
Miss Thunberg said she first heard about climate change aged about eight years old. "I was just very moved," she said.
"When I was 11 I became very depressed," she added.
"It had a lot to do with the climate and ecological crisis. I thought everything was just so wrong and nothing was happening and there's no point in anything."
After realising she could make a difference, she said she promised herself that "I was going to do something good with my life".
The teenager also admitted that, when she first told her parents of her plan to miss school every Friday, they "weren't very fond of that idea".
In the wide-ranging BBC interview, Miss Thunberg said that having Asperger's had helped her in life: "It makes me different, and being different is a gift, I would say. It also makes me see things from outside the box.
"I don't easily fall for lies, I can see through things. If I would've been like everyone else, I wouldn't have started this school strike, for instance."
Asked what she would say if she met US President Donald Trump, she said: "I can't really say anything to him that he hasn't heard before.
"Obviously he's not listening to the science and to what we have to say, so I wouldn't be able to change his mind."
In 2017, Mr Trump announced the US would withdraw from the 2015 Paris agreement on tackling climate change.