"Outrage is understandable, but violence is never acceptable," he said in a statement shortly after the graphic video was released.
The video shows five now-former Memphis Police Department officers initially pulling over Nichols.
The officers throw him to the ground, try to cuff him and use a taser before Nichols escapes and runs away but is later caught and beaten.
Nichols is heard calling out "Mom!" as officers punch, kick him in the face, use pepper spray and a baton before his body goes limp.
