US President Donald Trump said on Wednesday he had asked Secretary of State Mike Pompeo to "closely study the South Africa land and farm seizures" and the killing of farmers there.
President Cyril Ramaphosa announced on August 1 that the ruling African National Congress was going ahead with plans to change the constitution to allow the expropriation of land without compensation.
Mr Trump's tweet appeared to be a response to a Fox News report on Wednesday that focused on South Africa's land issue and murders of white farmers.
Since the end of apartheid in 1994, the ANC has followed a "willing-seller, willing-buyer" model under which the government buys white-owned farms for redistribution to blacks. Progress has been slow.
South Africa's state-owned Land Bank said on Monday a plan to allow the state to seize land without compensation could trigger defaults that could cost the government $2.8 billion (Dh10.3bn) if the bank's rights as a creditor are not protected.
Mr Trump's tweet comes days after it was announced that his wife, Melania, will travel to Africa in October for her first major solo international trip as first lady.
In January, South Africa protested to the US embassy in Pretoria about reported remarks by Mr Trump that some immigrants from Africa and Haiti come from "s**thole" countries.
South Africa's foreign ministry called the remarks, which sources said Mr Trump made during a meeting on immigration legislation, "crude and offensive" and said Mr Trump’s subsequent denial was not categorical.