In an interview with KNTV, Zimmerman said his motive for selling the gun was political.
"Anything I can think of to ensure that Hillary Clinton doesn't become leader of the greatest nation on earth," Zimmerman said.
Clinton supports tougher gun control laws and spoke last weekend at a conference organized by the Trayvon Martin Foundation to help mothers who have lost children or family members to gun violence.
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Zimmerman also said he plans to donate some of the proceeds from his gun sale to officers killed by violence tied to the Black Lives Matter movement.
"I would sell everything and anything I own to ensure, to attempt to ensure, that they can no longer hurt men and women of law enforcement," he said.
Zimmerman told KNTV he has gained strength from the hardship he endured after he shot and killed the unarmed 17-year-old boy in 2012 in self-defense.
He said the subsequent murder trial taught him to think clearly under pressure.
But Zimmerman also said if he had known what was going to happen that day, he would have stayed in bed.