The White House is firing back at “South Park” … after the popular animated TV show brutally roasted Donald Trump to kick off its 27th season last night.

ICYMI … in the season premiere, Trump is shown in bed with Satan — hinting he’s down for a little devilish action. But Satan’s not into it, and instead takes a jab at the size of Trump’s microscopic weener. Ouch.

WH spokesperson Taylor Rogers tells TMZ … “This show hasn’t been relevant for over 20 years and is hanging on by a thread with uninspired ideas in a desperate attempt for attention. President Trump has delivered on more promises in just six months than any other president in our country’s history – and no fourth-rate show can derail President Trump’s hot streak.”

She takes aim at the show’s creators, Matt Stone and Trey Parker, saying … “Just like the creators of South Park, the Left has no authentic or original content, which is why their popularity continues to hit record low.”

“South Park” didn’t only go after the prez …  it also poked fun at Stephen Colbert’s late-show cancellation, even though Paramount is technically their boss, too. Guess it’s all fair game when you’re part of the same corporation — nothing like roasting your own backyard!

Paramount was also mocked over Trump’s “60 Minutes” lawsuit settlement, with anchors nervously kissing up to him and Jesus himself showing up at the protest ’cause “it was part of a lawsuit and the agreement with Paramount.”