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SAN FRANCISCO - For the past week Mitt Romney has slammed President Obama for his "you didn't build that" line. Tonight Obama responded, accusing his GOP rival of "splicing and dicing" his words for political gain.

"Earlier today Gov. Romney was at it again, knowingly twisting my words around to suggest that I don't value small businesses," the president told supporters in Oakland, Calif.

"In politics, we all tolerate a certain amount of spin. I understand these are the games that get played in political campaigns. Although … when folks just like omit entire sentences of what you said - they start kind of splicing and dicing - you may have gone a little over the edge there," he said.

Obama was referring to recent attacks by Romney that suggested the president had denigrated small business owners and their pursuit of the American dream.

Speaking in Roanoke, Va., 10 days ago, the president said, "If you were successful, somebody along the line gave you some help. … Somebody helped to create this unbelievable American system that we have that allowed you to thrive. Somebody invested in roads and bridges. If you've got a business - you didn't build that. Somebody else made that happen.

"The point is, is that when we succeed, we succeed because of our individual initiative but also because we do things together," he said at the time.

Republicans and the Romney campaign have since seized on Obama's "you didn't build that" line.

Earlier today, Romney, also in California, convened a roundtable of business leaders beneath a banner bearing the slogan "We did build it!" in mocking reference to Obama.

"I hear it time and again, people say as you did, that they think business is the enemy or that business is getting a free ride. And there's a sense that some of you are bad guys," Romney said, alluding to the president. "I see you as the good guys. You're employing people and hiring people."

Get more pure politics at ABC News.com/Politics and a lighter take on the news at OTUSNews.com

Tonight Obama tried to clarify. "I believe with all my heart that it is the drive and the ingenuity of Americans who start businesses that lead to their success. I always have and I always will," he said.

What makes small businesses successful is a strong and growing middle class, he said, accusing Romney of pursuing policies that only look out for the wealthy.

"Mr. Romney's plan is to gut these investments just so that he can give more tax breaks to millionaires and companies that are shipping jobs overseas. He thinks that's the best way to grow the economy. He thinks that's the best way to help small businesses. And I've got to tell you he is dead wrong. We did not build this country from the top down. We built this country together," Obama said.