Gardner owned the Soft Sheen Hair Care Company. He has led several protests recently calling for the city and contractors to hire more African-American workers.
Thursday, Gardner targeted a construction site at 87th and the Dan Ryan.
Gardner is urging Mayor Rahm Emanuel and the City Council to take action.
"Here you have the disrespect to us to have nothing but non-Afro-Americans working in the middle of the black community building a gas station which is primarily going to service the black community," said Gardner.
"It's who I hired, and who they hired, because I'm a contractor, I hire subcontractors," said general contractor Rick Scali.
There was a meeting Thursday afternoon between Gardner and several city officials. The mayor's office called it "positive," saying everyone agreed to continue to collaborate to ensure equal opportunities for African0Americans.
Gardner said the mayor has a "responsibility to be fair."