Isakson, one of the Republicans who attended, organized the guest list for the dinner on Wednesday night at the White House.
"Most of the conversation was driven by the members the president allowed to come and most of the conversation was about debt, deficit — our growing national debt, our fiscal policy, and reforming entitlements," Isakson said Thursday on CNN's "Starting Point." "It was a very meaningful three-hour discussion, a free-flowing exchange from both sides."
The dinner was the second of its type. Obama previously dined with 12 Senate Republicans in March at a restaurant at the Jefferson Hotel.
Isakson said Obama mainly listened to Republicans at the dinner and worked to respond to comments from each one.
"The president opened the dinner by saying 'I'm here to listen,' " Isakson said. "And he did and he didn't take notes. He responded specifically about items that he brought up. We talked about areas of common interest, of common ground. We talked about differences. We did what you have to do to build a foundation for solving problems."
White House officials on Wednesday night said Obama had enjoyed a "constructive and wide-ranging discussion" and looked forward to more bipartisan dialogue.