Paul, a Texas Republican and a leading GOP presidential candidate, told CNN he did not write the comments.
USA Today reported some issues of the newsletters also included anti-gay and anti-Israel comments.
But on Wednesday, Paul told CNN he had nothing to do with the content of his newsletters, published when he was out of Congress in the 1980s and 1990s.
"Why don't you go back and look at what I said yesterday on CNN and what I've said for 20-something years, 22 years ago?" Paul said in a CNN interview Wednesday. "I didn't write them. I disavow them. That's it."
He then removed his microphone abruptly, ending the interview.
Since 2001, Paul has attempted to disavow racist and other incendiary language in the newsletters.
But he had acknowledged writing some of the passages when first asked about them in a 1996 interview with The Dallas Morning News.
In that interview, Paul told the News he made the comment about black men in Washington while writing about a 1992 study by the National Center on Incarceration and Alternatives, a criminal justice think tank in Virginia.
He cited the study in the newsletter, which read, in part, "Given the inefficiencies of what D.C. laughingly calls the criminal justice system, I think we can safely assume that 95 percent of the black males in that city are semi-criminal or entirely criminal."
He told the News: "These aren't my figures. That is the assumption you can gather from the report."
Also in 1996, Paul did not dispute having written in his 1992 newsletter, "If you have ever been robbed by a black teenaged male, you know how unbelievably fleet of foot they can be."
Paul spokesman Jesse Benton said the congressman was practicing medicine when the newsletters were published and "did not write or approve the incendiary passages and does not agree with them."