The civil rights activist told a TMZ photographer outside LaGuardia Airport in New York City that he was disappointed in Saturday's acquittal.
"We always had a plan B. We now go to the Justice Department seeking civil rights charges," he said. "We're not gonna stop until we get justice."
Earlier Sunday, in an appearance on NBC's "Meet the Press," Sharpton said he disagreed with the verdict.
"We now have a position on the books, in the state of Florida, where an unarmed teenager who committed no crime can be killed and the killer can say self-defense," he said. "That is dangerous. That is an atrocity. And I think that must be addressed."