“The City of Cape Town is taking the lead in South Africa in addressing these difficult issues of race,” she said in an open letter to Ramaphosa on Sunday.
“I call on you to send me the evidence to back up your claims made in Parliament. I will use that evidence in my engagements and take direct action.”
De Lille was responding to comments made by Ramaphosa while answering oral questions in the National Assembly on Wednesday.
Ramaphosa reportedly spoke about incidents where black people were treated badly in restaurants, blocked from booking into certain hotels and found it difficult to rent flats in the Western Cape.
He called on the provincial leadership to stand up and say it was not right and not allowed.
In her letter to the deputy president, De Lille said she launched a campaign to address the issue of racist incidents.
“Over the next few weeks, I will be engaging industry bodies to find ways in which we can prevent these incidents from occurring.
“I take your allegations seriously and ask you to join me in tackling these issues head-on,” she wrote to Ramaphosa.