The cable channel was to air Irving's lecture with a lecture by Deborah E. Lipstadt, a professor of Holocaust studies at Emory University in Atlanta who had gone to court with Irving.
Irving had sued Lipstadt for libel for calling him a Holocaust denier, but Britain's Royal High Court of Justice dismissed the suit in 2000 saying the British writer was anti-Semitic and deliberately manipulated historical evidence.
Lipstadt was due to give a lecture promoting her new book, "History on Trial: My Day in Court With David Irving," but pulled out once she heard Irving's lecture would be covered as well, the New York Times reported Friday.
The David S. Wyman Institute for Holocaust Studies began circulating a petition in support of Lipstadt after hearing about C-Span's plan. The petition gathered more than 200 signatures in two days.
C-Span taped Irving's lecture last weekend in Atlanta, but a spokeswoman for the network said management had not decided whether to air the tape.