US President Donald Trump is going after director Spike Lee, who used his Oscar acceptance speech to urge mobilisation for the 2020 election.
Trump tweeted on Monday that Lee did a "racist hit on your President".
Trump claimed that he had "done more for African Americans" than "almost" any other president.
Lee won for Best Adapted Screenplay for his white supremacist drama BlacKkKlansman, sharing the award with three co-writers.
The film includes footage of Trump after the violent white supremacist protests in Charlottesville, Virginia.
Lee did not directly name Trump.
He spoke about black history and his family history, saying his grandmother's mother was a slave, before stressing the presidential election next year.
Said Lee: "Let's all be on the right side of history. Make the moral choice between love versus hate."
Lee's Oscar win was his first ever — a long-awaited achievement in a film career spanning decades. He was also nominated for Best Director.
An ecstatic Lee jumped into presenter Samuel L. Jackson's arms when he took the stage.
According to the Post, previously, the Brooklyn-raised Lee had only received a Best Screenplay nod for Do The Right Thing in 1990 and a Best Documentary Feature nomination in 1998 for 4 Little Girls.
He won neither, but received an honorary award in 2015 for being "a champion of independent film and an inspiration to young filmmakers."
When Ryan Seacrest asked Lee, during E!'s red carpet coverage before the ceremony, if those slights were "water under the bridge," the director replied, "I wouldn't go that far."
BlacKkKlansman was also nominated for Best Picture, Best Supporting Actor (Adam Driver), Best Director (Lee), Score and Editing.