Rev. Al Sharpton invited the parents of Michael Brown.
Cleveland officers thought the boy was brandishing a weapon.
Protests spread to New York City, D.C., Seattle, Minneapolis, Oakland and Cleveland.
He said "acts of violence threaten to drown out those who have legitimate voices."
Midway through Obama's remarks, protesters began criticizing his deportation policy.
After the ruling, the order was put on hold so the state can consider an appeal.
ABC's interview is Darren Wilson's first public remarks about the fatal shooting.
Police body cameras could ensure accountability in light of the shooting in Ferguson, Mo.
"Something is wrong with criminal justice in America," the senator wrote.
"We sacrifice the safety of others by creating chaos," Cleaver said.