President Barack Obama has offered a very personal take on the death of Trayvon Martin, saying that 35 years ago, he could have been the unarmed black teen shot dead by a neighborhood watchman.

Civil rights rallies were scheduled in cities across the country Saturday following the July 13 verdict in the closely followed, racially charged Florida shooting case.

In a surprise appearance before reporters Friday, Obama hailed the "incredible grace and dignity" of Martin's parents and warned that a resort to violence would "dishonor" his death.

He also called for a review of controversial "stand your ground" laws like the one in place in Florida, which assert that citizens can use lethal force -- rather than retreat -- if they sense their lives are at risk.

"When Trayvon Martin was first shot, I said that this could have been my son," Obama said, in his first substantive comments on a verdict that has aroused an impassioned debate on US race relations.

"Another way of saying that is Trayvon Martin could have been me 35 years ago."

While he refrained from direct comment on the jury's decision to acquit volunteer watchman George Zimmerman, Obama weighed in on the larger issues of race raised by the case.

"I just ask people to consider if Trayvon Martin was of age and armed, could he have stood his ground on that sidewalk?" Obama asked.

"And do we actually think that he would have been justified in shooting Mr Zimmerman who had followed him in a car because he felt threatened?

"And if the answer to that question is at least ambiguous, then it seems to me that we might want to examine those kinds of laws," he said.

The teen's parents Tracy Martin and Sybrina Fulton said they were "deeply honored and moved" by Obama's comments.

"President Obama sees himself in Trayvon and identifies with him. This is a beautiful tribute to our boy," they said in a statement.

"We seek a future when a child can walk down the street and not worry that others see him as dangerous because of the color of his skin or the clothes on his back."

As supporters rally on Saturday, Fulton is due to appear in New York and Tracy Martin expected to speak in Miami.

In Congress, meanwhile, Democratic Senator Dick Durbin said he would hold hearings on the US gun lobby's role in promoting "stand your ground" laws in 30 US states.

Trayvon Martin, 17, was fatally shot on the rainy night of February 26, 2012, during an altercation with the 29-year-old Zimmerman in a gated community in Sanford, Florida.

Zimmerman said he acted in self-defense and his team did not specifically invoke the "stand your ground" law in its arguments.

A jury of six women, all but one white, cleared him of second-degree murder and manslaughter charges.

Verdict critics argue that Zimmerman racially profiled the youth -- who had no criminal record -- and was able to kill him with impunity because of a biased criminal justice system.

But Zimmerman -- who has a white father and a Peruvian mother -- insists that race was not a factor in the incident.

Obama urged better training of law enforcement at the state and local levels "to reduce the kind of mistrust in the system that sometimes currently exists."

He said young African American males needed greater encouragement in the face of negative stereotypes that many blacks believe were at the root of the shooting death.

"There are very few African American men in this country who haven't had the experience of being followed when they were shopping in a department store. That includes me," he said.

"There are very few African American men who haven't had the experience of walking across the street and hearing the locks click on the doors of cars.

"That happens to me -- at least before I was a senator."

"And I don't want to exaggerate this, but those sets of experiences inform how the African American community interprets what happened one night in Florida," he said.

Calling for "some soul searching" on race, Obama urged that it be pursued in families, churches and workplaces rather than by politicians.