Sharpton and the Rev. Horace L. Sheffield III, pastor of New Galilee Missionary Baptist Church, talked about the campaign outside the Motown Historical Museum.
Sharpton said it made sense to promote the hip-hop campaign in Detroit because NAACP leaders plan to conduct a mock funeral for the "N" word during the group's July convention in the city.
"The 1960s were the Motown sound and James Brown," Sharpton said as he stood in front of the museum, which includes the former Motown Records studio. "But they did not call us the 'N' word and they did not degrade women."
The campaign began last month in New York City with Sharpton challenging the recording industry on denigrating lyrics. Organizers say they plan to soon roll out the effort in Los Angeles.
The bars of soap will be donated to shelters and halfway houses for women, organizers said.