South Africa rejects the allegation that white people are disproportionately targeted by crime.
Murder rates are high in the country and the overwhelming majority of victims are black.
"We have many people that feel they're being persecuted, and they're coming to the United States. So we take from many ... locations, if we feel there's persecution or genocide going on," Trump said in the Oval Office.
"Generally, they're white farmers and they're fleeing South Africa, and .... it's a very sad thing to see. But I hope we can have an explanation of that because I know you don't want that."
After a friendly initial chat in which Trump complimented South African golfers and Ramaphosa said he wanted to talk about critical minerals and trade, Trump played a video that purported to show evidence of the persecution of whites.
It featured a a communist politician playing a controversial anti-apartheid song that includes the lyrics "kill the farmer".
Ramaphosa mostly sat expressionless while the video was played, occasionally craning his neck to look at it.
Trump said the video showed the graves of thousands of white farmers.
Ramaphosa said he had not seen that before, and that he would like to find out what the location was.
Trump then displayed printed copies of articles that he said showed white South Africans who had been killed, saying "death, death" as he flipped through them.
Ramaphosa said there was crime in South Africa, and the majority of victims were black.
Trump cut him off and said: "The farmers are not black."
Ramaphosa responded: "These are concerns we are willing to talk to you about."
When a reporter asked Trump for his view on whether a genocide is underway in South Africa, he said, "I haven't made up my mind".
In recent months, Trump has criticised South Africa's land reform law aimed at redressing the injustices of apartheid and its genocide court case against Israel.
He has cancelled aid, expelled South Africa's ambassador and offered refuge to white minority Afrikaners based on racial discrimination claims that officials in Pretoria say are unfounded.
Trump has accused South Africa of seizing land from white farmers and of fuelling violence against white landowners with "hateful rhetoric and government actions".
South African authorities say these claims are inaccurate and "fail to recognise South Africa's profound and painful history," meaning its long history of domination by white colonialists, enshrined in the "apartheid" system.
