Ms Trump, a vocal critic of Mr Trump, wrote the explosive tell-all book about the president’s family and his upbringing: Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man.
Speaking in an interview with CNCBC on Thursday, Ms Trump described how she had found the entire convention “disturbing” but in particular her extended family’s endorsement’s of the president.
“The idea of passing him off like a great family man is like trying to pass him off as a great businessman,” she said.
She added: “It’s disturbing to watch honestly, the whole thing has been disturbing but that in particular.”
She called on Americans to “forget” their party politics and “pay attention to what’s happened to this country”.
“Look at what he does not at what other people, who are related to him or paid by him, say about him. We have so much evidence that he doesn’t care about other people,” she said.
“I’m not sure why the American people continue to be fooled by the rhetoric.”
All of Mr Trump’s four adult children spoke over the three-day convention, praising his leadership and appealing for voter support in the November election.
The president’s niece, however, has launched a staunch campaign against Mr Trump in an attempt to prevent him from securing a second term.
Her revealing book, published in July, became a best-seller after a New York Supreme Court judge ruled that she was free to release and talk about the president’s private life.
In response to the book, White House press secretary Kayleigh McEnany previously said that it is full of “falsehoods”.
“It’s ridiculous, absurd allegations that have absolutely no bearing in truth,” Ms McEnany said.
Even more recently, Ms Trump released a series of secret recordings with Maryanne Trump Barry, in which Mr Trump’s sister can be heard criticising his leadership.
“He has no principles. None. None,” one recording says. “And his base, I mean my God, if you were a religious person, you want to help people. Not do this.”
The recordings were released just a day after a White House memorial service for Robert Trump, the younger brother of the president and Ms Barry.
Mr Trump was dismissive of the recordings, saying in a statement: “Every day it’s something else, who cares. I miss my brother, and I’ll continue to work hard for the American people.”
The Trump campaign did not immediately respond to request for comment when contacted by The Independent.
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