"With all due respect, I don't get confused," Ms Haley told Fox News television.

She was responding to comments by White House economic adviser Larry Kudlow.

On Sunday Ms Haley said the US was preparing new sanctions against Russian firms. But the White House later said no such action had yet been decided.

In her initial remarks, made on CBS television, Ms Haley said the fresh measures would target "any sort of companies that were dealing with equipment related to [Syrian President Bashar al-] Assad and chemical weapons use".

She said, the new sanctions would send a "strong message" to Russian leaders.

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The statement angered President Donald Trump, The New York Times reported. The spat became public on Tuesday, when Mr Kudlow sought to clarify the administration's position on the sanctions.

He said Ms Haley was "doing a great job", adding: "There might have been some momentary confusion about that. I think the issue here is we have a set of sanctions and additional sanctions are under consideration but have not been determined."

Analysis by Anthony Zurcher, BBC North America reporter

Nikki Haley has been one of the few top members of the Trump team who has carved out space apart from the president's dominating influence. She's been a forceful foreign policy voice in an administration that has undercut, and churned through, other members of the presidential national security and international affairs team.

Being situated in New York and not Washington has probably helped - but her good fortune may be ending. First, the president reportedly blocked one of her senior aides, who was anti-Trump in 2016, from becoming Vice President Mike Pence's national security adviser. Then came the stern White House rebuke after her announcement on Sunday of forthcoming sanctions on Russia.

It's the sort of public dressing down that has led some to suggest she resign in protest. A New York Times article hints that there may be a longer game here, however - a budding alliance between Ms Haley and Mr Pence that could lay the groundwork for a Republican future after Mr Trump.

If that includes even the hint of contingency plans for 2020, when Mr Trump says he will run for re-election, the newly tense relations between the president and Ms Haley could quickly reach a breaking point.

After Ms Haley denied being "confused", in an interview hours later, Mr Kudlow called her to apologise, the New York Times reported.

"I was wrong to say that," he told the newspaper. "She was basically following what she thought was policy. The policy was changed and she wasn't told about it, so she was in a box."

However observers say the exchange has highlighted rifts within the Trump team.

Ms Haley is regarded as a major foreign policy figure in the administration, especially since the dismissal of Secretary of State Rex Tillerson last month.

Tensions between Russia and Western countries have risen since the US, the UK and France carried out strikes in Syria last week in response to an alleged Syrian chemical weapons attack.

Russia and Syria, its ally, insist that no chemical attack took place in the rebel-held town of Douma on 7 April.