TLC is speaking out in support of transgender teen Jazz Jennings after she was verbally attacked by Duggar family member Derick Dillard.

Dillard unleashed a social media rant on the 16-year-old, saying ... "Transgender" is a myth. Gender is not fluid; it's ordained by God." He made the comments while her show, "I Am Jazz," was airing Wednesday night on TLC ... where the Duggars used to be top dog.

A TLC rep tells TMZ ... Dillard's "personal statement" in no way reflects the network's views.

TLC pulled the plug on "19 Kids & Counting" after Josh Duggar's child molestation scandal broke in 2015 -- so Dillard's comments do smack a little of sour grapes.

Dillard still has TLC ties though -- his wife, Jill Duggar, is set to star on an upcoming show called "Counting On."