"We will not allow the Grand Jury's decision to set us back. We view this as a beginning, not an end. We look forward to working with people from all concerned communities to bring a new era of change and end the fear and suffering of communities targeted and harassed by police," said Denise Lieberman, a civil rights lawyer campaigning for justice over Brown's killing.
As many as a dozen buildings were set ablaze Monday night. A deployment of 2,200 National Guardsmen arrived in Ferguson in convoys of armored vehicles, bolstering armed police who set up roadblocks to stop a second night of riots.
The Ferguson protests were mirrored by linked protests in Los Angeles, Seattle, New York and other metropolitan areas Tuesday night. In New York, protesters briefly shut down the Brooklyn Bridge and disrupted traffic elsewhere. Hundreds blocked traffic in Cleveland, Ohio, in a separate demonstration over the fatal shooting of a 12-year-old boy by a police officer.
"It's rooted in realities that have existed in this country for a long time," the president added.
Police officer Darren Wilson was under investigation for the killing of Michael Brown, an unarmed 18-year-old, who he fatally shot during an arrest on August 9, sparking weeks of often-violent protests in the suburb.
After three months of closed-door talks, a randomly-selected Missouri grand jury chose not to indict the police officer. Wilson told jurors he had fired in self-defense after Brown pushed him back into his car, hit him and grabbed at his drawn gun.