New York Times notes, he went on to seemingly encourage Congress to get involved:

Mr. Obama, who has been saying that the nation should look ahead rather than focusing on the past, said he is “not suggesting” that a commission be established.

But in response to questions from reporters in the Oval Office, he said, “if and when there needs to be a further accounting,” he hoped that Congress would examine ways to obtain one “in a bipartisan fashion,” from people who are independent and therefore can build credibility with the public.

Obviously, Obama's not keen about this because he's focused on moving forward with his political agenda, and he's afraid a partisan fight over holding Republicans accountable for their lawbreaking during the Bush years will derail that.

In other words, it will take courage. We'll be watching to see how much he actually possesses.