First lady Melania Trump thanked Chelsea Clinton for standing up for her son, Barron Trump.

"Thank you @ChelseaClinton - so important to support all of our children in being themselves! #StopChildhoodBullying," the first lady wrote Tuesday night on Twitter.

Melania Trump's tweet was sent during President Trump's rally in Phoenix, which included chants of "lock her up" when Clinton's mother, Hillary, was mentioned.

The first lady's thanks came after the former first daughter denouncing a tweet that appeared to target the 11-year-old son of President Trump. (The account that sent the tweet is now set to private, so the tweet is unavailable.)

In response to the tweet from @mattyren, Clinton wrote, "Dear Matty-Barron is A KID. No child should be talked about in the below manner-in real life or online. And for an adult to do so? For shame."

Clinton also defended the youngest Trump son on Monday, after a story from the conservative Daily Caller criticized Barron Trump's clothing.

More:Chelsea Clinton defends Barron Trump's right to 'private childhood'

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