US President Donald Trump’s Twitter attack on Nordstrom for dropping his daughter Ivanka’s clothing line has raised concerns about the use of his White House platform for his family’s businesses.

In response to the Twitter comment Trump posted criticising Nordstrom, which has said its move was based on the sales performance of the Ivanka Trump products, White House spokesman Sean Spicer characterised the company’s action as a “direct attack” on the president’s policies.

“My daughter Ivanka has been treated so unfairly by @Nordstrom. She is a great person — always pushing me to do the right thing! Terrible!,” Trump said on Wednesday in his post on both his personal and official presidential Twitter accounts.

Trump’s comments underscore the complicated relationship that the wealthy New York real estate developer who became president has with his sprawling family business interests amid criticism from Democrats and others about the ethics and legality of the arrangement.

During a White House briefing, Spicer painted Nordstrom’s action as an attack on the president’s daughter.

“For someone to take out their concern with his policies on a family member of his is just not acceptable. And the president has every right as a father to stand up to them,” Spicer said.

Nordstrom did not respond to requests seeking comment. A spokeswoman for the Ivanka Trump brand declined to comment.

In a statement last week, Nordstrom said it routinely cuts brands each year and that the decision to pass on the Ivanka Trump brand had been based on its performance.

A day after Nordstrom’s statement, luxury retailer Neiman Marcus Group also said it had stopped selling Ivanka Trump’s jewelry line on its website and a store in New Jersey, according to Yahoo News.

The move by the retailers comes amid an ongoing campaign called #GrabYourWallet, which encourages shoppers to boycott products with ties to President Trump, his family and his donors.

Shares of Nordstrom fell 0.7 per cent after the president’s criticism but recovered to trade up 3.7 per cent at $US44.38 on the New York Stock Exchange.

Nordstrom later said its decision to drop Ivanka Trump branded merchandise from its stores and online was based on the brand’s performance.

“Over the past year, and particularly in the last half of 2016, sales of the brand have steadily declined to the point where it didn’t make good business sense for us to continue with the line for now,” the retailer told Reuters.

Nordstrom said it informed Ivanka Trump about its decision in early January.

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