Defence Minister Ehud Barak says in excerpts aired today that "at the moment of truth, the answer given was that the ability didn't exist."
It quotes former Mossad chief Meir Dagan as telling Prime Minister Benjamin Netanyahu that the order was illegal, as it needed Cabinet approval.
The full programme is scheduled for broadcast tomorrow.
Israel views Iran as an existential threat due to its nuclear programme, frequent calls for Israel's destruction and support of anti-Israel militants.
The West suspects Iran might try to build nuclear weapons. Iran denies that. Israel has hinted at a military strike if economic sanctions fail.
"The chief of staff must build the operational capacity, he must tell us from a professional point of view whether it is possible to carry out an order, or if it is not possible, and he also can, and must, give his recommendation, (but) it can be carried out against his recommendation," Barak said.
Ashkenazi, on the other hand, claims in closed talks that he did prepare the military option, and that the IDF was ready for a strike, but he was convinced that this would be a strategic mistake.
"This is not something you do unless you're certain you want to see it through," Channel 2 quoted Ashkenazi as saying.
The report cited "sources close to Ashkenazi" as explaining that such a move would create "facts on the ground" that invariably would lead to war.
Dagan has come out in public against an Iran strike a number of times over the past few years.
In his first public appearance after hanging boots in May 2011, he said that a strike on Iran would be the 'dumbest' thing to do.
Ashkenazi has also publicly stated his opposition to an Iran strike since laying down his uniform, preferring continued covert activities to foil Iran's nuclear ambitions.
"I think that also today we must carry out a covert campaign, everything that is below the threshold of war, the threshold of a strike," he told a meeting of the Council for Peace and Security, an association of national security experts in Israel, last August.
The two retired officials had a very difficult relationship with their political bosses towards the end of their tenure, something that grabbed a lot of media attention.
Jerusalem: An Israeli news programme claims that Israel's premier told his military to prepare for a strike on Iranian nuclear sites in 2010, but it was not ready.
First Published: Monday, November 05, 2012, 17:56