The UK Independence Party leader wants to take Britain "backwards" and divide rather than unite, Cameron said, as both sides in the referendum debate prepared to make a final push before the Thursday vote.
He made the argument as the battleground shifted to the news media with large rallies still on hold because of the Thursday slaying of Labor Party lawmaker Jo Cox.
Cameron praised the compassionate vision of an inclusive Britain upheld by Cox, who had publicly backed the "remain" side, in contrast to Farage and the other advocates for a British withdrawal from the 28-nation EU bloc, the Associated Press reported.
It is not clear what impact, if any, the shocking killing of Cox will have on the vote.
A 52-year-old man has been charged with murder over her death. When asked his name in court Saturday, the suspect said "death to traitors, freedom for Britain."