Obama waited six days before talking about the verdict. George Zimmerman was found not guilty on charges of second degree murder and manslaughter for shooting and killing Martin in a condominium complex in Sanford, Florida.
Zimmerman, who was armed with a handgun, was part of the neighbourhood watch organisation that patrolled the development against potential criminals.
Martin was staying in the complex and had gone out on a rainy evening last year to buy snacks at a local store. He was spotted by Zimmerman as he walked back to the residence. He was wearing a sweatshirt with the hood pulled up against the weather.
Zimmerman called the police to report that he thought Martin was acting suspiciously. The dispatcher told Zimmerman not to follow Martin because police were on the way. Zimmerman ignored that request, followed Martin and a scuffle or fight apparently took place during which Zimmerman shot the teen.
Police initially did not charge Zimmerman because he said he was acting in self-defence. Florida's stand-your-ground law, which is on the books in some other states, allows the use of deadly force if a person feels their life is in danger.
Obama said the country needed to re-examine such laws: "I'd just ask people to consider, if Trayvon Martin was of age and armed, could he have stood his ground on that sidewalk?"
Obama said it was important to put the angry reaction of many African Americans into context.
Protests were understandable, he said, adding that "some of that stuff is just going to have to work its way through as long as it remains nonviolent".
- AP