South Africa's foreign ministry says the US ambassador has "apologised unreservedly" for claiming the country sold weapons to Russia.
EDnews informs via foreign media that on Thursday Reuben Brigety alleged a Russian ship was loaded with ammunition and weapons in Cape Town last December.
South Africa says it has no record of an arms sale and President Cyril Ramaphosa has ordered an inquiry.
On Friday the White House national security spokesman would not be drawn on details of the allegations.
But John Kirby said it was a "serious issue" and the US had consistently urged countries not to provide support for Russia's war in Ukraine.
Writing on social media after meeting the foreign ministry, Mr Brigety said he was "grateful for the opportunity to... correct any misimpressions left by my public remarks".
He said in the conversation he "re-affirmed the strong partnership between our two countries and the important agenda our presidents have given us".
Meanwhile a South African cabinet minister hit out at such "megaphone diplomacy", saying South Africa could not be "bullied by the US".