The Republican lawmaker also said he has concerns about the constitutionality of legislation that would ban assault weapons but would support such a bill if written narrowly, as he has in the past.
"The bad guys aren't affected by gun control," Giuliani said during an interview that aired Saturday on Fox's America's News Headquarters. "You tell them they can't have an assault weapon, they say go to hell, we're going to have our assault weapon."
He said the only solution is pro-policing, which means taking away guns from the "bad guys"
Giuliani said the president's plan also would intrude on what some people consider to be their right to privacy.
"I always thought the right to protect the public was paramount in that situation," he added.
A new Fox News poll shows 71 percent of registered voters think tougher gun laws won't stop school shootings like the one Dec. 14 inside a Newtown, Conn., elementary school in which 20 first-graders and six adults were killed.
Giuliani echoed such thoughts, telling Fox that stricter gun laws will instead reduce the rights of law-abiding Americans and further arm criminals.