The White House says Donald Trump was standing up for his daughter when he tweeted, criticising the department store Nordstrom.
He claimed Ivanka Trump was treated "so unfairly" by the company, which has stopped selling her clothing and accessory line.
A spokesman for the US president says he was responding to an "attack on his daughter".
My daughter Ivanka has been treated so unfairly by @Nordstrom. She is a great person -- always pushing me to do the right thing! Terrible!— Donald J. Trump (@realDonaldTrump) February 8, 2017