President-elect Donald Trump called Meryl Streep "one of the most over-rated actresses in Hollywood" after she took aim at him during the Golden Globes.
The Hollywood actress and three-times Oscar winner, 67, criticised Mr Trump in front of the star-studded audience, while not naming him directly.
She said his actions legitimised bullying, citing the moment he appeared to ridicule a disabled reporter.
Mr Trump responded on Twitter, writing: "Meryl Streep, one of the most over-rated actresses in Hollywood, doesn't know me but attacked last night at the Golden Globes.
"She is a Hillary flunky who lost big. For the 100th time, I never 'mocked' a disabled reporter (would never do that) but simply showed him 'grovelling' when he totally changed a 16 year old story that he had written in order to make me look bad.
"Just more very dishonest media!"
Streep, who has a record 19 Oscar nominations, supported Hillary Clinton during the presidential election campaign.
She was even reported to have got into character as Mr Trump, complete with spray tan, fake belly and an oversized red tie, during a gala benefit.
The actress gave her speech while picking up a gong for outstanding contribution to entertainment.
She criticised Mr Trump's impression of a disabled reporter, saying it "kind of broke my heart".
"There was one performance...that stunned me. It sank its hook in my heart not because it was good, there was nothing good about it, but it was effective, and it did its job," she said.
"It made its intended audience laugh and show their teeth. It was that moment when the person asking to sit in the most respected seat in our country imitated a disabled reporter, someone he outranked in privilege, power, and the capacity to fight back. It kind of broke my heart, and I saw it, and I still can't get it out of my head because it wasn't in a movie. It was real life.
"And this instinct to humiliate when it's modelled by someone in the public platform by someone powerful, it filters down into everybody's life because it kind of gives permission for other people to do the same thing.
"Disrespect invites disrespect. Violence incites violence. When the powerful use definition to bully others, we all lose."
Streep said: "Hollywood is crawling with outsiders and foreigners, and if we kick them all out, you'll have nothing to watch but football and mixed martial arts, which are not the arts."
Previously, Mr Trump dismissed the actress as "a Hillary lover".
In a telephone interview with The New York Times, he denied he had intended to make fun of the paper's reporter, Serge F. Kovaleski.
"People keep saying I intended to mock the reporter's disability, as if Meryl Streep and others could read my mind, and I did no such thing," he said.
Despite the criticism, Mr Trump said he was sure other stars would turn out for his inauguration ceremony later this month.
He said: " We are going to have an unbelievable, perhaps record-setting turnout for the inauguration, and there will be plenty of movie and entertainment stars.
"All the dress shops are sold out in Washington. It's hard to find a great dress for this inauguration."