UNTV
Now playing
01:33
Greta Thunberg: You are failing us. How dare you
Joe Manchin
CNN
Joe Manchin
Now playing
02:03
'I never thought in my life ...' Why Manchin won't walk away from bipartisanship
Gaetz speaks to members of the media outside the hearing Michael Cohen, former attorney and fixer for President Donald Trump, testifies at before the House Committee on Oversight and Reform at Rayburn House Office Building February 27, 2019 on Capitol Hill in Washington, DC. Last year Cohen was sentenced to three years in prison and ordered to pay a $50,000 fine for tax evasion, making false statements to a financial institution, unlawful excessive campaign contributions and lying to Congress as part of special counsel Robert Mueller's investigation into Russian meddling in the 2016 presidential elections.
Alex Wong/Getty Images
Gaetz speaks to members of the media outside the hearing Michael Cohen, former attorney and fixer for President Donald Trump, testifies at before the House Committee on Oversight and Reform at Rayburn House Office Building February 27, 2019 on Capitol Hill in Washington, DC. Last year Cohen was sentenced to three years in prison and ordered to pay a $50,000 fine for tax evasion, making false statements to a financial institution, unlawful excessive campaign contributions and lying to Congress as part of special counsel Robert Mueller's investigation into Russian meddling in the 2016 presidential elections.
Now playing
06:11
'Bombastic, antagonistic, unapologetic': A look at Gaetz's political career
Former House Speaker John Boehner attends a ceremony to unveil a portrait of himself on Capitol Hill, Tuesday, Nov. 19, 2019 in Washington.
Michael A. McCoy/AP
Former House Speaker John Boehner attends a ceremony to unveil a portrait of himself on Capitol Hill, Tuesday, Nov. 19, 2019 in Washington.
Now playing
02:42
Boehner says Republican colleague held 10-inch knife to his throat outside House floor
President Joe Biden, accompanied by Vice President Kamala Harris, and Attorney General Merrick Garland, speaks about gun violence prevention in the Rose Garden at the White House, Thursday, April 8, 2021, in Washington.
Andrew Harnik/AP
President Joe Biden, accompanied by Vice President Kamala Harris, and Attorney General Merrick Garland, speaks about gun violence prevention in the Rose Garden at the White House, Thursday, April 8, 2021, in Washington.
Now playing
02:05
Biden calls for ban on assault weapons
CNN
Now playing
02:22
Biden: High-speed internet is infrastructure
AFP/Getty Images
Now playing
03:24
Donald Trump breaks his silence on Matt Gaetz
CNN/WLOX
Now playing
01:43
'He says the quiet part out loud': Borger reacts to GOP election official's remark
AFP/Getty Images
Now playing
02:30
Haberman: Trump had to be talked out of defending Matt Gaetz
CNN
Now playing
03:26
Georgia's Lt. governor says elections law was a result of Trump's misinformation
Now playing
02:38
GOP lawmakers can't give examples of why states need anti-transgender sports bills
CNN
Now playing
03:04
Avlon reacts to McConnell's advice to corporations
WASHINGTON, DC - APRIL 06:  U.S. President Joe Biden delivers remarks on the state of vaccinations in the U.S. in the State Dining Room of the White House April 6, 2021 in Washington, DC. President Biden announced that states should make all adults eligible for COVID-19 vaccine by April 19.  (Photo by Alex Wong/Getty Images)
Alex Wong/Getty Images North America/Getty Images
WASHINGTON, DC - APRIL 06: U.S. President Joe Biden delivers remarks on the state of vaccinations in the U.S. in the State Dining Room of the White House April 6, 2021 in Washington, DC. President Biden announced that states should make all adults eligible for COVID-19 vaccine by April 19. (Photo by Alex Wong/Getty Images)
Now playing
01:12
'Smarten up': Biden admonishes states' restrictive voting laws
WAVE
Now playing
01:27
'It's stupid': McConnell's warning for corporate America
reality check thumb
reality check thumb
Now playing
02:48
John Avlon breaks down fraud claims among Trump donors
Now playing
06:22
Key figure in Gaetz extortion claims responds
(CNN) —  

President Donald Trump mocked Swedish climate activist Greta Thunberg on Twitter late Monday night after the 16-year-old excoriated world leaders for not doing enough to tackle the climate crisis.

“She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!” Trump posted on Twitter, replying to a video of Thunberg’s speech at the United Nations climate action summit earlier in the day.

Trump’s penchant for Twitter insults and online confrontations with people he sees as political adversaries is well known, though Monday’s tweet is a striking display of the President teasing a child.

Thunberg appeared to take Trump’s slight in stride. By late Tuesday morning, she had updated her Twitter bio to read: “A very happy young girl looking forward to a bright and wonderful future.”

In the video shared by Trump of her speech, Thunberg is visibly frustrated and at times appears to be holding back tears of anger as she dresses down the UN General Assembly.

“People are suffering, people are dying, entire ecosystems are collapsing. We are in the beginning of a mass extinction and all you can talk about is money and fairy tales of eternal economic growth,” Thunberg said.

She did not name Trump or any other world leaders in her speech, but her message was pointed.

“How dare you continue to look away and come here saying that you’re doing enough when the politics and solutions needed are still nowhere in sight,” she said. “You say you hear us and that you understand the urgency, but no matter how sad and angry I am, I do not want to believe that. Because if you really understood the situation and still kept on failing to act then you would be evil and that I refuse to believe.”

Former White House communications director Anthony Scaramucci, who recently withdrew his support for Trump, criticized the President for his comment about Thunberg.

“Parents in America and around the world: he went after a 16 year old girl yesterday. ⁦@realDonaldTrump⁩ unfit to serve,” Scaramucci tweeted on Tuesday.

Trump briefly attended the UN climate summit on Monday in an impromptu stop on his way to his administration’s priority event on religious freedom. But the US did not speak at the event and Trump – who has repeatedly said he thinks climate change is a hoax – left after 15 minutes.

Thunberg, who has helped galvanize a global movement demanding more action to address climate change, crossed paths with Trump at the UN General Assembly. Video captured her staring down the US President.

The young Swede has been open about her diagnosis of Asperger’s, calling it a “superpower” that helps her activism.

“My diagnosis has definitely helped me keep this focus. When you are interested about something you just continue to read about it and you get super focused,” she told CNN’s Bill Weir in an interview this month.

CNN’s Nicole Gaouette and Ivana Kottasová contributed to this report.