An online gun auction website yanked George Zimmerman's ad to sell the pistol he used to kill unarmed black teenager Trayvon Martin, saying it wanted no part in the deal, but a second site offered to post it.

A listing for the weapon was removed from the GunBroker.com site Thursday morning, minutes after the auction was to begin, as negative traffic about the sale exploded online. In a statement posted on its website, GunBroker.com said listings are user generated, and that the company reserved the right to reject listings at its discretion.

Zimmerman never contacted anyone at the site and no one there "has any relationship with Zimmerman," the company wrote in its statement.

It added, "We want no part in the listing on our web site or in any of the publicity it is receiving."

Hours later, United Gun Group tweeted that it would post Zimmerman's ad. The new link was posted, along with a statement from Zimmerman. However, the site apparently went down a few minutes later. The site calls itself a "social market place for the firearms community."

Critics called the planned auction an insensitive move to profit from the slaying.

Zimmerman had told Orlando, Florida, TV station WOFL that the pistol was returned to him by the U.S. Justice Department, which took it after he was acquitted in Martin's 2012 shooting death.

The auction for the 9 mm Kel-Tec PF-9 pistol was to begin at 11 a.m. EDT Thursday and end 24 hours later.

Zimmerman's listing said a portion of the proceeds would go toward fighting what Zimmerman calls violence by the Black Lives Matter movement against law enforcement officers, combatting anti-gun rhetoric of Democratic presidential candidate Hillary Clinton and ending the career of state attorney Angela Corey, who led Zimmerman's prosecution.

The listing ended with a Latin phrase that translates as "if you want peace, prepare for war."

Zimmerman, now 32, has said he was defending himself when he killed Martin, 17, in a gated community near Orlando. Martin, who lived in Miami with his mother, was visiting his father at the time.

Zimmerman, who identifies as Hispanic, was acquitted in Martin's February 2012 shooting death. The case sparked protests and a national debate about race relations. The Justice Department later decided not to prosecute Zimmerman on civil rights charges

Lucy McBath, the mother of another black teenager shot by a white man during an argument at a Jacksonville convenience store in 2012, said the auction reflected a "deplorable lack of value for human life."

"I am deeply disappointed that the man who killed Trayvon Martin is trying to sell the very gun he used to cut that precious life short to raise money," McBath said in a written statement.

The slaying of her son, 17-year-old Jordan Davis, by Michael Dunn drew parallels at the time to the Zimmerman-Martin case. Dunn told police he had felt threatened by Davis. Unlike Zimmerman, Dunn was convicted of murder.

Since Zimmerman was acquitted, he has been charged with assault based on complaints from two girlfriends. Both women later refused to press charges and Zimmerman wasn't prosecuted. His estranged wife, ShellieZimmerman, also accused him of smashing her iPad during an argument days after she filed divorce papers. No charges were filed because of lack of evidence. They were divorced in January.

Orlando-based attorney Mark O'Mara has previously represented Zimmerman. A receptionist in O'Mara's office said Thursday that he no longer represents Zimmerman and had no comment.

Martin's parents declined to address Zimmerman's actions in statements made through representatives.

Martin's mother, Sybrina Fulton, said through an attorney that she would rather focus on her work with the Trayvon Martin Foundation than respond to "Zimmerman's actions."

Daryl Parks, whose firm represented the Martin family during the trial, is now chairman of Fulton's foundation. He says Fulton is pushing for policies that protect youth and address gun violence.

Fulton also founded the Circle of Mothers conference, a three-day event to help mothers who have "lost children or family members" to gun violence. Democratic presidential candidate Hillary Clinton will be keynote speaker at the event in Fort Lauderdale starting May 20.

In the auction listing, Zimmerman cited strong interest from collectors including "The Smithsonian Museum in Washington DC."

Smithsonian spokesman John Gibbons denied any interest.

"The Smithsonian has never expressed an interest in collecting this firearm and has no intention of collecting or displaying this firearm," Gibbons said.