Since the 1951 Angleton-Harel Secret Pact, there has been an unwritten agreement that CIA and Mossad will not spy on each others countries. Kiriakou (who is a wonk) confirmed as much in recent remarks.
But no one without at least a TS really knows
There's written legislation saying the CIA/NSA/etc. can't spy on Americans.
Guess what happens anyways?
He has CIA experience but his word shouldn't just be taken at face value. The man has unsettling views on buying pardons and excuses some other things away as well. Kiriakou shouldn't be trusted, IMO.
That said, he probably isn't wrong at all about this particular thing.
I think he said in that interview that the CIA does not spy on Israel. It does not apply the other way around. Based on policy decisions, this seems very believable to me.
Kiriakou also stated several times that the Mossad was known to casually try to recruit CIA agents:
https://youtu.be/R7OWqAgGzwA?t=163