"I'm more concerned if we do not get to the truth and get to what actually happened, and bring justice to this situation, then there is going to be a problem in the streets," he said on CBS's "Face the Nation."
Tensions have calmed in the St. Louis suburb in the last few days, something Clay attributes to Attorney General Eric Holder's visit.
Clay said he promised the Brown family he would do everything to make the investigation transparent. And he expressed confidence in the FBI review.
Clay said there has to be a broader discussion about policing of the black community. In addition, he called for all law enforcement to have cameras in their police cars and on their uniforms.
"There needs to be a frank discussion about how we change the way the Africa-American community is policed," he said. "These people were sworn to serve and protect, and apparently that is not happening here."
Clay is scheduled to speak at the funeral Monday. In addition, three members of the Obama administration will attend: Broderick Johnson, Marlon Marshall and Heather Foster.
Johnson is chairman of the administration's My Brother's Keeper task force; Marshal is the deputy director of the White House Office of Public Engagement; and Foster also works in the Office of Public Engagement and is a St. Louis native.