Secretary of State Marco Rubio said on Tuesday the US was announcing a new visa restriction policy targeting some foreign nationals from South Africa as President Donald Trump's administration continues to cool ties with the country.

The Trump administration has criticised South Africa over a range of issues including actions aimed at addressing racial inequality that Trump claims hurt the African nation's white population.

Washington has also criticised land reform policies and South Africa's genocide case against Israel at the International Court of Justice, over the US ally's assault on Gaza.

The visa curb policy targets "foreign nationals who are responsible for, or complicit in, the enactment or implementation of laws or policies that enable uncompensated land seizures, race-based discrimination, and/or the incitement of imminent violence against members of minority ethnic or racial groups in South Africa," Rubio said in a statement.

"The South African government has not adequately addressed the previously laid out concerns," Rubio said.

The South African embassy in Washington did not immediately respond to a request for comment.

Pretoria says there is no evidence of discrimination or persecution ​against white people and that ideas of white racial superiority are a threat to South Africa's post-apartheid unity, its sovereignty and its diplomatic relations. President Cyril Ramaphosa has called for global efforts to debunk false stories about white persecution.

Trump has previously cut aid to South Africa, offered refuge to white minority Afrikaners, expelled the country's ambassador and made false claims of white genocide in the African nation.

Trump's portrayal of South Africa as dangerous and oppressive for white people also aligns with some of his domestic policies that have targeted diversity initiatives aimed at addressing historic inequities for marginalised groups. Trump casts them as discriminatory against white people and men.

Rubio's statement on Tuesday did not identify any person by name.

Three decades after the end of apartheid in South Africa, some fringe groups lament the loss of white power that democracy brought. While South Africa has one of the highest murder rates in the world, most victims are Black.