According to PA the PM said of his former party treasurer “I rather think I do owe him an apology”:

“I rather think I do owe him an apology. Had I known at the time how badly the journalists had behaved, I might have been in the position to take a different approach. I am very sorry about that. I congratulate Peter Cruddas on his victory and on the verdict he has won. I think it is very deserved. He has done a huge amount for this country. I look forward to meeting him after the summer.”

Which is not the same as actually giving him in one.

Sorry seems to be the hardest word…

UPDATE: 

Labour are enjoying this:

“If David Cameron thinks he owes Peter Cruddas an apology, perhaps he should invite him round to one of his famous dinners for donors in Downing Street to tell him to his face.”