Giuliani, who personally supports civil unions but not same-sex marriage, said that he was against the recent vote in New York to legalize gay marriage in the state. But while he called that decision "wrong," he described it as a "democratic vote" and urged Republicans to move on.
"I think that marriage should be between a man and a woman, but I think that the Republican Party would be well-advised to get the heck out of people's bedrooms and let these things get decided by states," Giuliani said. "I think it's wrong, but there are other things that I think are wrong that get decided by democratic vote."
He said he doesn't see "harm" coming to New York over the new law.
"I see more harm, however, by dwelling so much on the subject of gays and lesbians and whether it's right or wrong in politics," Giuliani said, in an interview with CNN's "State of the Union."
Some congressional Republicans are pushing to defend the federal Defense of Marriage Act, which defines marriage as between a man and a woman, though lawmakers in Washington are far more focused on deficit and debt concerns.
Giuliani was addressing the debate over social issues as he decides his next step. Giuliani, who ran unsuccessfully for the GOP presidential nomination in 2008, is one of a handful of big Republican names still deciding whether to make a late entrance into the 2012 field.
Giuliani said he has not made up his mind, but that he should be able to "figure it out" by the end of the summer. He stood by his record in New York.
"I think that I probably have the best record in terms of having done something similar to what the country needs done right now. I look at the other candidates, and they have all done very impressive things, but none of them really had to take over a city, one of the largest economies in the country and one of the most complex when it was in terrible trouble and turn it around and have definable results," he said.