The president's brother, Robert Trump, is attempting to stop the publication of Too Much and Never Enough: How My Family Created the World's Most Dangerous Man, which is due for publication by Simon & Schuster on 28 July.
Mary Trump's lawyer, Theodore J. Boutrous Jr, and her publisher, Simon & Schuster, promised an immediate appeal. Robert Trump argues Mary Trump must comply with a written agreement among family members that such a book can not be published without permission from other family members.
"We are disappointed that the Court has granted this Temporary Restraining Order", the publishing house said in a statement.
But an attorney for Robert - who told The New York Times earlier this month that Mary's book was "a disgrace" - said he was "very pleased" by the temporary block.
In dueling statements on Tuesday, Mary and Simon & Schuster likened the judge's decision to censorship and said they would appeal it - while Robert's attorney celebrated the ruling. We will immediately appeal. "This book, which addresses matters of great public concern and importance about a sitting president in an election year, should not be suppressed even for one day".
"We look forward to vigorously litigating this case and will seek the maximum remedies available by law for the enormous damages caused by Mary Trump's breach of contract and Simon & Schuster's intentional interference with that contract", Mr Harder said.
Mary, a 55-year-old clinical psychologist living on Long Island, had been set to share revealing details of her years in the Trump family, according to Simon & Schuster.
Mary Trump once stood up to her uncle Donald.
The lawsuit claims that under the terms of the family members' agreement regarding Fred Trump's will, in the event she violates the agreement Mary Trump consents to an injunction.
The lawsuit states that when Trump's father Fred Trump died in 1999, there had been objections over the will.
President Trump said in an interview with The Post previous year that he made mistakes in dealing with his brother and regretted pushing him to join the family business. She and her brother, Fred III, said in court papers that someone in or connected to the Trump family got Fred Sr.to change his will and give them less than they expected.
A NY judge has temporarily blocked President Donald Trump's niece from publishing a damning tell-all memoir about the First Family.
He ordered that the parties present their arguments on July 10 or as soon as possible thereafter.