Comedian Kathy Griffin says she has received death threats and is under Secret Service investigation after posting a video that depicted her holding the severed, bloody head of President Donald Trump.

Speaking to media with her attorney Lisa Bloom, the embattled US comedian who was this week sacked by network CNN and dropped from a TV commercial, fought back tears, alleging the Trump family had broken her and killed her career.

Griffin said while her apology for the stunt “absolutely stands”, that she had made a mistake and felt “horrible” for her failed joke, she also branded Mr Trump and his family “bullies” for their reaction to the sketch.

“A sitting president of the United States and his grown children and the First Lady, are personally, I feel, personally trying to ruin my life forever,” Griffin said referring to a barrage of commentary from the Trump family and their supporters on social media.

Griffin said she didn’t think she would have a career after this and said Mr Trump had “broken” her.

“I’m teasing the President because this is America, and you shouldn’t have to die for it,” Griffin said. “The death threats that I’m getting are detailed and constant, serious and specific.”

Mr Trump tweeted this week that Griffin “should be ashamed of herself” for the “sick” stunt, adding that his son, Barron, 11, was having a “hard time with this.”

Melania Trump also released a statement calling the photo “very disturbing”.

“When you consider some of the atrocities happening in the world today, a photo opportunity like this is simply wrong,” Ms Trump wrote.

Kathy Griffin thought this video gag was funny – but the Secret Service isn’t laughing. Photo: TylerShields.com

Griffin told reporters the scandal was also a “woman thing” and she had dealt with older white guys trying to keep her down her whole life and career.

“I am a woman in a very male-dominated industry and field,” Griffin said.

At the press conference, Griffin’s criminal defence attorney Dmitry Gorin said the case was closed and they would fully co-operate with the Secret Service in their investigation.

The Secret Service declined to comment on the investigation on Friday.

“She (Griffin) basically exercised her First Amendment rights to tell a joke,” Mr Gorin told journalists.

Mr Gorin said entertainers made videos to express themselves, and that he had never seen an entertainer, let alone a comedian, be subjected to a criminal investigation.

“It’s really outrageous and I believe she’s going to be cleared,” he said.

Since the video was posted on Tuesday, the stand-up comedienne and star of NBC sitcom, Suddenly Susan, has lost her job co-hosting CNN’s New Year’s Eve special and had all her upcoming comedy shows cancelled.

Venues in New Jersey, New York, New Mexico, Pennsylvania and California cancelled upcoming shows.

The Community Art Theatre in Williamsport, Pennsylvania, posted on its website that the show had been dropped “due to the recent controversy surrounding Kathy Griffin and the concern for the safety and security of our patrons and staff”.

Republican Party spokesman Mike Reed called the press conference a “desperate attempt” to change the conversation.

“Kathy Griffin’s career was long over before she attempted to make a disgusting joke about decapitating the President,” Mr Reed said.

“What she did was wrong and President Trump and his family have every right to condemn it.”

When asked what she was thinking, the 56-year-old actor and comedian said the bloody head stunt was a play on Mr Trump’s sexist comments about Fox News Channel anchor Megyn Kelly that sparked outrage during the 2016 campaign for the Republican nomination.

After a torrid questioning by Kelly during a 2016 Republican debate, Mr Trump said moderator Kelly had had “blood coming out of her eyes” and added that she also “had blood coming out of her wherever”.

“I did it just to break a man’s record, and it broke my own record,” Griffin said.

– with AAP