South Africa has accused US President Donald Trump of seeking to sow division after his tweet referring to the "large-scale killing of farmers".
He said he had asked his secretary of state to look into the matter of "seizing land from white farmers".
South Africa's presidential spokeswoman said Mr Trump was "misinformed".
Last month, South Africa said it would go ahead with plans to amend the constitution, allowing land to be expropriated without compensation.
The redistribution of land was a fundamental principle of the governing African National Congress (ANC) during its struggle against white-minority rule.
But 24 years after apartheid ended, white people - who make up just 9% of the population - own 72% of the farmland held by individuals, according to government figures.
AfriForum, a group that campaigns for the interests of Afrikaners in South Africa, welcomed Mr Trump's move, saying it believed it had influenced the US president's views.
"Trump's announcement follows only three months after AfriForum sent a delegation to the USA to inform the Cato Institute (a prominent American think tank), Tucker Carlson (presenter of Fox News) and various other institutions and politicians of the situation in this regard in South Africa," it said in a statement.
The group lobbies globally on the issue, saying South Africa's white farmers feel under attack.
In March, Australia's then-home affairs minister said he was exploring giving South Africa's white farmers access to fast-track visas on humanitarian grounds amid fears over the number of farm killings.
But South Africa's government said it was ridiculous to suggest white farmers were being persecuted.
Have any farms been seized?
No. The constitution has not yet been changed and since 1994 the ANC has been following a willing-buyer willing-seller module to redistribute land.
Around 10% of land in white ownership has been transferred to black owners in this way.
Mr Ramaphosa told parliament on Wednesday that South Africa needed to speed up the pace of land reform to correct a historical injustice.
However, the South Africa president said it would be done in an ordered manner and there would be no land grabbing.
"As South Africans we must move away from this fear psychosis that has been going around, particularly those that have been spreading lies and rumours.
Organisations like AfriForum going overseas and saying that the ANC is out for a land grab."
Critics of expropriation without compensation have pointed to neighbouring Zimbabwe, which saw some violent attacks on white farmers, alongside the seizure of their land, which has been widely blamed for the the country's economic collapse.