The Rev. Al Sharpton spoke at the 10:30 a.m. and 12:30 p.m. services at the church at 2270 S. Harvard Blvd.
On March 2, 1991, Los Angeles police officers attempted to pull over Rodney King, who refused to stop. After a pursuit, King's car was cornered, and he was beat by police repeatedly using batons and even kicking him at times. A bystander videotaped the entire beating. It was broadcast, sparking outrage and fueling racial tensions.
Violence and civil unrest erupted in South Los Angeles on April 29, 1992 a few hours after the four police officers involved in the King beating were acquitted of assault charges.
The riots lasted six days, leaving 53 people dead and more than 2,000 injured. Property damage totaled a billion dollars.
First AME Church served as a shelter for evacuees, and on Sunday it again became a place for people to gather in peace.
"What happened to Rodney King should have never happened, and what we responded to should have never happened," Sharpton said. "Violence is not an option in fighting violence."
In the years since the riots, the church's Assistance Corporation has worked with the public and private sector to help people get jobs and further their education.
The Rev. John Hunter, AME's pastor, said Sunday's service focused on the aftermath of the riots and how far the city has come since then.
"While we know we've made great progress, certainly Trayvon Martin indicates to us and brings to the conscious of the country that we still have progress to be made," Hunter said.
During the riots, South Los Angeles resident Dolores McLemore said she sensed the danger, but was out in the streets to warn the innocent.
"I walked a block back and started telling people they need to turn around, and I actually had talked to Reginald Denny when he pulled out. I said 'You need to turn back,' and he tried ... but the truck was too big," McLemore said. "I felt it was a sad thing. But the people had a different mentality at that moment and I had never seen a riot mentality before."
Volunteers on Sunday marked the anniversary of the riots by helping to transform a vacant lot where a grocery store was destroyed 20 years ago.
Volunteers with LA Works and other community groups planted trees and prepared the soil for a community garden on a lot in the 8700 block of South Vermont Avenue. People who live in this neighborhood will not only be able to enjoy the garden, they'll also be able to plant and eat their own fruits and vegetables grown on this plot of land.
City News Service contributed to this report.