"If Ivanka was not doing a great job, I would essentially, but in a nicer way, tell her, 'You're fired,'" he said. The same holds true for her two brothers, Donald Jr. and Eric, who are also employed by their father.
But there seems to be no chance of that happening anytime soon, with Ivanka thriving in the fast-paced blood sport of international real estate.
"She is very serious, I guess she is ambitious, but I am not sure I like that word," Trump said. "She just loves what she does."
Everything hasn't always been easy for the heiress. When she was 9 years old, her world was rocked when her famous parents, Donald and Ivana Trump split. The divorce was played out across tabloid headlines.
"That was not particularly fun. Nobody wants to see, you know, the tabloid one liners, on the cover," she said. "When something like this happens, and you see your family and your home sort of crumbling, I think you start to really cling to people a little bit more, and my brothers and I became incredibly close in a relationship that extends to today."
As a first step in establishing her own family, Trump recently became engaged to Jared Kushner, the 28-year-old owner of the New York Observer and fellow real estate mogul, who, she said, is also her best friend. Kushner gave her a nearly 6-karat diamond engagement ring, designed by the head of her jewelry line.
The driven couple shares a passion for work, going into the office on Sundays. "We work two blocks from each other on Sundays too. I can actually look out my window and see into his window," she said. "We spend time together, albeit, not directly together on our Sundays."
Trump declined to discuss her recent conversion to Judaism -- the newfound religion she now shares with her fiance.
"I've converted to Judaism not to marry him, but I am marrying him," she said, highlighting the distinction. "I choose not to talk about this because it think in life there are some things that are personal and between people, and once I open this can of worms everyone will think it's OK to have this discussion with me."
But for the heiress who seems to have it all, there's at least one thing she wants that she doesn't have.
"Personally, obviously, I want a family. You know that's something I'd love to have. A houseful of cute little kids ... like four or five," she said. "So that's something that I've got to get cracking, but I'm not there yet."
CLICK HERE to read an excerpt of Ivanka's new book, "The Trump Card: Playing to Win in Work and Life."