"I'm sure he did regret it," Baker said on CBS' "Face the Nation." "In fact I'm certain that he did."
He said that Reagan later worked to end Apartheid in South Africa.
"Once that happened and control of South African policy passed to the Congress, President Reagan was really determined to … meet with the black leaders of South Africa and deal with the problems of Apartheid. And he was able to do so," Baker said.
Baker, who met Nelson Mandela, called the leader an "extraordinarily beautiful human being."
"He had an enduring and endearing presence of dignity that I don't think I've seen on any other person," he said. "How many people forgive their captors when they've been imprisoned for 27 years?"