"I know you're trying," she told Democratic senators at an invitation-only forum, "but just not hard enough. Sorry."
Facing the Select Committee on the Climate Crisis, in which young activists were invited to give their personal testimony on climate change, the 16-year-old gave a speech lasting only 50 seconds, submitting a scientific report instead.
“I have not come to offer prepared remarks at this hearing, I am instead attaching my testimony," she said.
“It is the IPCC Special Report on Global Warming of 1.5C [SR1.5] which was released on October 8, 2018.”
“I am submitting this report as my testimony because I don’t want you to listen to me.
“I want you to listen to the scientists. And I want you to unite behind the science.
“And then I want you to take action.”
Ms Thunberg said instead of listening to her and other teenagers, lawmakers should invite scientists to the Capitol to listen to their expertise on ways to slow a rise in global temperatures.
"This is not about us. This is not about youth activism," she said.
"We don't want to be heard.
"We want the science to be heard."
Ms Thunberg was one of four young people invited to the "Voices Leading the Next Generation on the Global Climate Crisis" committee to provide a testimony on why they are advocating for action.
The report she submitted - the IPCC (Intergovernmental Panel on Climate Change) Special report - details the devastating impacts of global warming of 1.5C above the pre-industrial era levels.
The 2018 report explores recent trends in carbon emissions and international strategies on combating climate change, and whether they are effective.
Massachusetts Senator Ed Markey and other lawmakers hailed Ms Thunberg as a "superpower," noting that her activism has drawn a passionate following of children essentially challenging their elders to take action.
"Save your praise," Thunberg replied.
"We don't want it," she added, especially if officials intend to talk about climate change "without doing anything about it."
The Swedish teen has been in the US rallying with fellow teenage activists since the end of August, and has been in Washington for the past couple of days.
She also met with former US president Barack Obama, who tweeted: "Just 16, Greta Thunberg is already one of our planet’s greatest advocates.
"Recognising that her generation will bear the brunt of climate change, she’s unafraid to push for real action."
Ms Thunberg is renowned for starting a global movement of climate change awareness, and inspiring young people to take charge and hold politicians and big corporations accountable for their lack of action on the climate crisis.
Friday will see a global strike in which activists are calling for immediate action from the world's governments to halt global warming, reduce fossil fuel consumption and avert environmental catastrophe.
Ms Thunberg also set to speak at the UN Climate Change Summit on September 23.
To mark her appearance there next week, an Italian artist has created a giant portrait of her in a field near the northern Italian city of Verona.
Italian land-artist Dario Gambarin used a tractor and plough to produce the 27,000 square metre picture of the teen climate activist, along with the words 'Hope in the land Greta'.
The land artist titled his work: 'From the Land to our Planet'.
Mr Gambarin specialises in portraits that can only be appreciated from high up.
His previous portrait subjects have included US President Donald Trump, former US President Barack Obama and Pope Francis.