Supporters of the man had said that they wanted to raise money to pay for Scott Roeder's defense. They planned to auction off items including an Army of God manual, an underground publication for anti-abortion militants that describes ways to shut down clinics, including bombing.
Also on the auction list was a prison cookbook compiled by Shelley Shannon, the Oregon woman who shot and wounded Tiller in 1993 and was later convicted in a series of abortion clinic arsons and bombings.
"Based on the details we know about the anticipated listings, we believe these would violate our policy regarding offensive material," eBay said in a statement.
If the items were posted, eBay said it would remove them from the online marketplace site because the company "does not allow listings that promote or glorify violence, hate, racial or religious intolerance.
"We do not allow items that encourage, promote or instruct others to engage in illegal activity and will not be a platform for those who promote violence toward others," the company statement said.
Tiller had been the target of protests for most of the 36 years that he performed abortions at his Wichita clinic, where he practiced as one of the nation's few providers of late-term abortions. He was fatally shot in his church in May.
Roeder, 51, is charged with first-degree murder in Tiller's death and is being held without bond. His trial has been scheduled for January.
Dave Leach, a Des Moines, Iowa, abortion opponent who was organizing the auction, said Tuesday he had contacted eBay about what the auction would entail, and also to tell the company "that we're not out for glorifying violence. We're wanting to get a man to his right by a trial by jury."
Leach questioned eBay's decision to stop the auction for Roeder, but said that the decision doesn't surprise him. He said other projects are in the works to raise money for Roeder, who has been appointed public defenders, but was considering hiring private lawyers.
"The items that we're thinking of marketing have historical value in the history of freedom of speech in the pro-life movement," Leach said.