Mitt Romney said now is "not a time to be talking about the politics associated with what happened in Aurora" during an interview Monday, but said legislation he signed while governor of Massachusetts to ban weapons like those used in the Friday massacre was a "combination of efforts" of groups on both sides of the debate.

"The law that we signed in Massachusetts was a combination of efforts both on the part of those that were for additional gun rights and those that opposed gun rights, and they came together and made some changes that provided, I think, a better environment for both, and that's why both sides came to celebrate the signing of the bill," Romney told CNBC's Larry Kudlow, according to a transcript released before the evening airing of the interview. "Where there are opportunities for people of reasonable minds to come together and find common ground, that's the kind of legislation I like. The idea of one party jamming through something over the objection of the other tends to divide the nation, not make us a more safe and prosperous place. So if there's common ground, why I'm always willing to have that kind of a conversation."

As Massachusetts governor, Romney signed into law the first state ban on assault weapons. That ban outlawed the type of rifle, an AR-15, which was one of the guns used in Friday's shooting. Police say the suspect, James Holmes also used a shotgun and two pistols to kill 12 attending the midnight movie and injure 59 others.

In the interview, the presumptive GOP nominee stressed that it's time "to reach out to others in their community" and "get on to policy down the road."

"I still believe that the Second Amendment is the right course to preserve and defend and don't believe that new laws are going to make a difference in this type of tragedy," Romney said. "There are-were, of course, very stringent laws which existed in Aurora, Colorado. Our challenge is not the laws, our challenge is people who, obviously, are distracted from reality and do unthinkable, unimaginable, inexplicable things."

Both campaigns dialed down the rhetoric after Friday's tragedy, taking a pause from politics and both sides took down their ads in the state. On Friday, both President Obama and Romney changed their tone and instead of holding boisterous rallies turned them into short speeches remembering the victims and the senseless tragedy.

But, it was clear Monday both campaigns put their gloves back on and Romney admitted the short pause was over.

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"I think we are, but we're starting also with a level of thoughtfulness and seriousness that I think is appropriate in the aftermath of a tragedy of this nature," Romney said. "Obviously, the campaigns are under way. We're talking about our respective views and at the same time, our hearts are heavy as we think about the funerals that'll be held this week and the families that have been so tragically altered by virtue of the loss of life."

Kudlow asked if those poignant speeches by both candidates and the less negative tone could continue. Romney said, "It really would be nice" before going after Obama calling their campaign the negative one.

"I mean, I know that the president, when he called me and congratulated me on becoming the presumptive Republican nominee, said that America is-will benefit from a-an important and healthy debate," Romney said. "I haven't seen the healthy, important debate coming from the president's team. It's been almost all attack ads on all sorts of peripheral issues."

A recent study of a two week period ending in July found the two campaigns were quite similar when it came to slinging mud. Advertising trackers Kantar Media's CMAG found 89 percent of Obama's ads were negative, while 94 percent of Romney's ads were negative.