Former President Donald Trump's presidential campaign has been ordered to pay nearly $1.3 million in legal fees to former White House aide Omarosa Manigault Newman by a New York court arbitrator.

       The award, handed down on Tuesday, comes after Trump filed a complaint against Manigault Newman over her 2018 book, "Unhinged: An Insider's Account of the Trump White House," in which she called Trump a racist and suggested that he was in "real and serious" mental decline.

       A source with the Trump campaign told ABC News that Trump intends to appeal the ruling.

       Trump's arbitration complaint against Manigault Newman, with the American Arbitration Association in New York City in 2018, alleged that she was in breach of a 2016 confidentiality agreement.

       MORE: Book excerpt: Omarosa Manigault Newman's 'Unhinged: An Insider's Account of the Trump White House'

       In September, arbitrator T. Andrew Brown ruled that the former president's nondisclosure agreement with Manigault Newman was "unenforceable."

       Brown said in the ruling that the terms of the nondisclosure agreement were "highly problematic" because it did not adhere to typical legal standards -- describing it as "vague, indefinite, and therefore void and unenforceable."

       Drew Angerer/Getty Images, FILE

       Director of Communications for the White House Public Liaison Office Omarosa Manigault listens during the daily press briefing at the White House, Oct. 27, 2017 in Washington, DC.

       In Tuesday's decision, Brown said that Manigault Newman was "defending herself in a claim which was extensively litigated for more than three years, against an opponent who undoubtedly commanded far greater resources than did Respondent."

       Following the order, Manigault Newman's attorney tweeted, "$1.3 Million Attorney Fee and Cost Order Against the Trump Campaign Issued! (Highest known prevailing party attorney fee assessment against a President or Presidential Campaign)."

       MORE: White House slams Omarosa Manigault Newman's new book as 'riddled with lies and false accusations'

       During the 2016 presidential campaign, Manigault Newman served as a liaison to the Black community. In her subsequent role as director of communications for the Office of Public Liaison, she was the highest-ranking African American woman in the White House.

       She resigned from the position in December 2017 after reports of tension between her and then-Chief of Staff John Kelly.