The move by Netanyahu and Defense Minister Ehud Barak was blocked by military commanders and the director of the Mossad intelligence agency, the Channel Two station reported in a documentary screened Monday.
The incident in 2010 -- the program reporter, Ilana Dayan, said military censors prevented her from using the exact date -- suggests that Netanyahu and Barak were prepared to risk triggering a Middle East war even though it's generally accepted Israel doesn't have the firepower to knock out Iran's nuclear project.
Netanyahu and Barak, a former military chief of staff and Netanyahu's commander when both were in the elite Sayaret Matkal special forces unit in the 1970s, are the main proponents of launching pre-emptive strikes against what they publicly perceive as an existential threat to Israel.
Washington has repeated warned the hawkish Netanyahu not to act unilaterally and urged he give time for a multitude of U.S. and EU sanctions endorsed by the United Nations to take effect.
This dispute has been a major source of friction between them since Netanyahu began his second period as prime minister in 2009.
In the meantime, the United States is engaged in an increasingly tense armed confrontation with Iran in the Persian Gulf.
The Channel 2 program said Netanyahu and Barak ordered the military to raise its level of preparedness for action to "P Plus," a designation signifying imminent action, to prevent Iran building a nuclear weapon.
After Dagan went public, he famously declared that bombing Iran "is the stupidest thing I've ever heard."
As Mossad chief, he stepped up a clandestine war against Iran's nuclear project in a bid to forestall a war. His agents assassinated scientists and sabotaged it by infiltrating faulty equipment, and in 2009 apparently unleashed the notorious Stuxnet computer virus that destroyed part of the uranium-enrichment program.
Dagan and Ashkenazi have both since left office, Dagan after Netanyahu reportedly refused to extend his term as Mossad chief.
In recent weeks, when many feared Netanyahu might order a strike on Iran during the run-up to the U.S. presidential election, he's appeared to step back from pre-emptive strikes. But Middle Eastern and Western governments remain nervous that he might act unilaterally.
No one's really sure whether Netanyahu, who's displayed a zeal for wanting to hit Iran first, has really backed off.
Israeli generals have warned in recent weeks that such an attack would provoke an unprecedented missile assault on Israel by Iran, its allies Hezbollah in Lebanon and Hamas in the Gaza Strip, and possibly even war-wracked Syria.
Even without Syria, Israel's northern neighbor and longtime adversary, the others are believed to have large missile arsenals.
Iran's reported to have 200-300 Shehab-3 intermediate-range ballistic missiles operational, with more accurate Sejjil-2 weapons under development.
By Israeli count, Hezbollah has more than 43,000 missiles and rockets, including hundreds capable of hitting anywhere in Israel.
Hamas only has shorter-range weapons but these can now reach the southern edge of greater Tel Aviv, Israel's main urban and industrial conurbation.
Israeli planners say these adversaries could unleash several hundred missiles a day on Israel's cities and strategic targets and keep that up for two months.
Officials predict fatalities will be around 500 at most. But with reports of the parlous state of Israel's civil defense network, including a severe shortage of gas masks, many fear the death toll will be far higher.
Concerns were boosted Oct. 23 when a munitions plant in Sudan, an ally of Iran, was destroyed in an air raid widely blamed on Israel. Many saw that long-range attack as a rehearsal for a larger airstrike on Iran.
Meantime, Israeli forces are conducting what appear to be non-stop exercises, including Austere Challenge 2012, described as the largest missile defense drill conducted with U.S. forces.
Last week, two top generals warned that Israel must, for the first time in years, face "unexpected security developments" on several fronts simultaneously.