Steven Mnuchin, US President-elect Donald Trump's nominee for Treasury Secretary, said on Thursday that it was important to keep the US dollar strong in the long term, walking back Trump's earlier comments on the US currency.

In an interview with the Wall Street Journal published on Monday, Trump complained that the dollar was "too strong", suggesting that he favored a weaker dollar.

That was in contrast with previous US administrations in the past two decades, which typically said a strong dollar is in the country's best interests. The dollar on Tuesday dropped to its lowest level in a month following Trump's comments.

"I think when the president-elect made a comment on the US currency, it wasn't meant to be a long-term comment," Mnuchin said before the Senate Finance Committee. "It was meant to be that perhaps in the short term, the strength of the currency...may have had some negative impacts on our ability in trade."

"The currency is very, very strong and what you see is people all over the world wanting to invest in the US currency," said Mnuchin, who was a former Goldman Sachs banker, adding the long-term strength of the dollar "is important" .

"I will enforce trade policies that keep our currency strong on the world exchanges and create and protect American jobs. We will also make America the best place for companies to do business," he stressed.

Mnuchin said he would lead the tax reform for the Trump administration, and he believed tax simplification, fewer deductions and deficit-neutral were very critical for the tax reform plan.

"I think we want to make sure that tax reform doesn't increase the size of the deficit," he said.