Miami, Florida (CNN) - In an interview at a Hispanic forum in Miami on Wednesday, Mitt Romney accused Newt Gingrich of making an unfair attack on his immigration stance in a campaign radio ad, saying the ad used "terrible terms" in a manner that was "very sad" and "inappropriate."
Hours before, the Gingrich campaign acknowledged it had stopped running the Spanish language ad, which had referred to Romney as "the most anti-immigrant candidate" and drew censure from Florida Sen. Marco Rubio.
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Romney was asked about the ad at a "Meet the Candidates" forum in Miami hosted by Spanish-language television outlet Univision.
"It's very sad for a candidate to resort to that kind of epithet. It's just inappropriate," Romney told the moderator about the ad. "There are differences between the candidates on these issues but we don't attack each other with those kind of terrible terms."
Romney also fired back at comments Gingrich had made earlier that day at the forum, charging the GOP candidate had pandered to the Latino community and behaved in a manner "unbecoming" of a presidential hopeful.
On stage earlier that day, Gingrich mocked Romney for suggesting people in the country illegally would "self-deport" and leave the United States voluntarily if the federal government made it too difficult to live here without documentation.
Gingrich laughed when asked by the moderator about the proposal, and called it an "Obama-level fantasy."
"How close are you to breaking up laughing out loud at this fantasy?" Gingrich scoffed, painting Romney as out-of-touch. "I think you have to live in a world of Swiss bank accounts and Cayman Island accounts and automatic $20 million of income with no work to have some fantasy this far from reality."
Gingrich suggested a grandmother who had lived illegally in the country for years would never be pushed into wanting to leave, and said Romney was ignoring the "humanity" of undocumented immigrants already established in the country.
During his appearance, Romney said Gingrich had previously supported the idea of self-deportation.
"I recognize that its very tempting to come out to an audience like this and pander to the audience and say what you hope the audience will want to hear but frankly I think that's unbecoming of a presidential candidate," Romney said. "And I think that was a mistake on his part."
Romney emphasized to the audience he was "pro-immigrant" and pointed to the high rate of businesses started by immigrants in the United States. Romney advocates for a identification card system that would make it more difficult for people in the country illegally to find work, but has said it does not make sense to "round up" the millions of undocumented immigrants and deport them.
He joked with the moderator about the citizenship of his father George Romney, who was born in Mexico but was an American citizen.
Univision host Jorge Ramos asked Romney whether he might be considered the first Mexican-American president if he were to be elected.
"I would love to be able to convince people of that, particularly in a Florida primary," Romney joked.
– CNN Political Producer Shawna Shepherd contributed to this report.