Griffin and her attorney accused Trump and his family of trying to end the 56-year-old comedian's career and said the shoot was inspired by comments Trump made about television journalist Megyn Kelly in 2015.
Griffin, known for her role in the late 1990s sitcom "Suddenly Susan" and starring in an eponymous reality TV show "My Life on the D-List" a decade later, as well as for a long running stand-up career, apologized for the stunt on Tuesday, saying she "went too far".
"A sitting president of the United States and his grown children and the first lady are personally trying to ruin my life forever", Griffin said.
In a tweet, Trump called the photo "sick" and in a separate post, the first lady stressed that the video had negatively affected their 11-year-old son, Barron.
Attorney Lisa Bloom says Griffin has retained a criminal attorney, who also appeared at a Friday press conference in which Griffin apologized again for the images.
And Griffin insisted she wasn't going to stop making fun of Trump, adding, "He does provide a lot of material".
"After hearing from many Minnesotans who were rightfully offended, I've come to the conclusion that it would be best for her not to participate in the event we had previously scheduled", the Minnesota Democrat said.
The U.S. Secret Service, which is responsible for presidential security, has opened an inquiry into the photo of Griffin posing with the severed-head replica.
Venues in New Jersey, New York, New Mexico, Pennsylvania and California cancelled upcoming shows. At least five shows have been canceled since Griffin released the controversial image.
Republican Party spokesman Mike Reed called the press conference a "desperate attempt" to change the conversation.
While Kathy Griffin continues her sympathy crusade after weathering a storm of criticism for her awful Trump severed-head photo, sources say she's seething about how Anderson Cooper dropped her from his CNN New Year's Eve broadcast like a hot potato.
"What she did was wrong, and President Trump and his family have every right to condemn it".
But in Friday's press conference she said, "it's not right", explaining that she's been getting explicit and detailed death threats.