President Donald Trump mocked teen climate activist Greta Thunberg on Twitter on Thursday after she was named Time magazine's Person of the Year, calling her win "ridiculous" and suggesting she take anger management classes.

"So ridiculous," Trump tweeted. "Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill!"

Trump, who was Time's Person of the Year in 2016, was a finalist for the 2019 nomination.

So ridiculous. Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill! https://t.co/M8ZtS8okzE — Donald J. Trump (@realDonaldTrump) December 12, 2019

Thunberg soon updated her Twitter bio to reflect Trump's comment, writing: "A teenager working on her anger management problem."

"Currently chilling and watching a good old fashioned movie with a friend," she added.

The president's eldest son, Donald Trump Jr., also weighed in on Thunberg's selection, blasting the magazine's decision.

"Time leaves out the Hong Kong Protesters fighting for their lives and freedoms to push a teen being used as a marketing gimmick," he wrote. "How dare you?"

It was not the first time the president has made a mention of Thunberg.

In September, after she made an emotional speech at the United Nations, Trump appeared to mock the 16-year-old by tweeting that she "seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!”

Thunberg did not respond directly to the president but hours later updated her Twitter bio to mimic his tweet.

Thunberg, who has Asperger’s syndrome, was asked to speak on climate change in front of several high-profile entities, such as the United Nations and Congress.

"I shouldn't be up here," she said in her September U.N. speech.

"I should be back at school on the other side of the ocean," the teen from Sweden said. "Yet, you all come to us young people for hope. How dare you? You have stolen my dreams and my childhood with your empty words."

Democrats responded to Trump's barb throughout the day, criticizing him for taking aim at the teenager.

"What kind of president bullies a teenager?" tweeted former Vice President Joe Biden, a leading 2020 Democratic contender, adding that Trump "could learn a few things from Greta on what it means to be a leader."

"Does the President really not have anything better to do today than attack a 16 year old?" tweeted Sen. Tim Kaine, D-Va.

Trump's tweet even came up at Thursday's House Judiciary Committee markup of the articles of impeachment against the president.

Rep. Hakeem Jeffries, D-N.Y., mentioned Trump's mocking of Thunberg while listing individuals who Trump has blasted.

"Are you here to defend that as well?" Jeffries asked Republicans of Trump's post.