Counselor to U.S. President Donald Trump Kellyanne Conway on Thursday promoted the clothing and jewellery line named after his daughter Ivanka, one day after the president's tweet criticizing a retailer for dropping her product line drew criticism over using public office for personal business gains.

"Go buy Ivanka's stuff," Trump senior adviser Kellyanne Conway told Fox News in an interview from the White House. "I'm going to get some myself today."

On Thursday, Ivanka's brand was thrust again into the headlines after her father attacked department store chain Nordstrom in a highly unusual move using a White House Twitter platform to intervene in a commercial matter.

"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 tweeted on Wednesday.

Nordstrom's shares dipped after the tweet, sent from both Trump's personal and official presidential accounts, but later closed up 4.0 percent on the New York Stock Exchange. Its shares were little changed in pre-market trade Thursday morning.

The move prompted criticism of Trump by ethics officials who served past Republican and Democratic administrations and said Trump's tweet was both unprecedented and troublesome.

White House spokesman Sean Spicer defended Trump's tweet on Wednesday, telling reporters that "the president has every right as a father to stand up" for his daughter.

Conway said on Thursday also backed Trump's comment, telling Fox News: "He's been a champion for women empowerment, women in the workplace."

Ivanka Trump has said she would step away from her company when her father took office in the White House.

A spokeswoman for the Ivanka Trump brand declined to comment on Wednesday.

Nordstrom has defended its decision to drop Ivanka's wares, citing performance.

Retailers still selling Ivanka Trump products include Macy's Inc (M.N), TJX Cos (TJX.N), Hudson’s Bay Co (HBC.TO), which runs high-end chains like Lord & Taylor, and Dillards Inc (DDS.N). Retailers that have dropped Ivanka Trump include Neiman Marcus NMRCUS.UL and HSN Inc (HSNI.O)

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