Gingrich said after reading that, he felt Romney was not worthy of congratulations.
"They outspent me five to one to quote destroy Newt Gingrich?" Gingrich told CNN. "You know, I think that doesn't deserve congratulations. I think that's reprehensible, I think it's dishonest, and I think it's shameful."
I feel very comfortable with exactly what happened after Florida," Gingrich added.
Romney hit Gingrich for not calling him during an appearance Wednesday on the Today Show, noting that both Rick Santorum and Ron Paul had called - as had he when the shoe was on the other foot in South Carolina.
"The other candidates all called, but I guess Speaker Gingrich doesn't have our phone number," Romney said.
Gingrich warned that Romney's brutal attacks could undermine his eventual general election campaign.
"Pretty hard to see how somebody is going to negatively carpet-bomb their way to the nomination," Gingrich said. "Pretty hard to see how that nomination is going to be worth much if that's all they've got to show for themselves."
Gingrich's appearance on CNN was fresh on the heels of a fiery rally in Las Vegas where he told supporters "it isn't good enough for the Republican Party to nominate Obama-lite." Gingrich also released a new web video that referred to the GOP frontrunner as "approved" by George Soros, a fundraiser for Democrats and progressive causes.
Romney's campaign dismissed Gingrich's attacks Friday as last-ditch attempts for attention.
“Newt Gingrich’s flailing attacks are the sign of a candidate trying to distract from his own record to save his sinking campaign. Newt Gingrich would rather make misleading statements about Mitt Romney’s record than tell Nevada voters suffering from the housing crisis why he took $1.6 million from Freddie Mac or why he filmed a climate change ad with Nancy Pelosi that was funded by George Soros," said Romney spokeswoman Amanda Henneberg.