But despite the match penalties, she renewed her attack at a media conference later.
"You will never, ever, ever be on another court of mine as long as you live". You are a liar.
Defending her outburst during the emotion-filled match, the talented mother has come out swinging, saying she is fighting for women's right and equality.
Seemingly motivated by the violation, Williams went on a mini-run to take a 3-2 lead, but her momentum was stymied after Osaka produced a critical serve break.
Williams was looking to win her 24th Grand Slam singles title, which would have tied her with Australia's Margaret Court for the all-time record.
The presentation ceremony began with more booing from the crowd before a tearful Williams said, to wild cheers: "I don't want to be rude".
Others widely shared Sally Jenkin's op-ed in the Washington Post, in which she said that the umpire "abused his authority". But the Grand Slam committee ruled that what she did "did not rise to the level of a major offense" and so she didn't face the additional disciplinary action that she could have been subject to after what happened in 2009. "I just want you to know that". Let's not boo any more.
A few games later, Williams received another warning, this time for smashing her racket, and that second violation automatically cost her a point, leading to more arguing.
Osaka, playing against her hero, managed to keep her calm to see out the victory.
Smirking 'Plaid Shirt Guy' Upstages Trump During Montana Rally
Trump's campaign rallies are often characterised by raucous interactions among supporters, Trump, and, sometimes, protesters. Trump said similar things when he tweeted about the op-ed on Wednesday - though he suggested the Times made up the report.
"I didn't get coaching. I have never cheated in my life!"
The opening set was nearly one-way traffic as the Japanese player controlled the rallies from the back of the court and appeared to show no nerves whatsoever.
The fall-out from this final is likely to rumble on for some time, with the long-time coaching partnership between Williams and Mouratoglou now under real strain.
Osaka had six aces compared to Williams' three aces in the final. The money comes out of her prize money of $1.85 million as the runner-up.
United States great Billie Jean King was among those coming down hard on Serena's side in her claim that chair umpire Carlos Ramos penalized her for comments that a male player could have gotten away with. "I'd rather lose", she told the umpire.
USTA Chairman and President Katrina Adams issued a statement as well, lauding Williams for her "great deal of class and sportsmanship". One of those being a player is not allowed to receive coaching during a tournament match.
"I'm telling you right now, I don't cheat to win". Osaka beat Williams in straights sets to win her first Grand Slam title.
"It was always my dream to play Serena in the US Open finals".
"The star of the show has been once again the chair umpire".
"If it was men's match, this wouldn't happen like this".