"To our regret, there is no Israeli military capability that would enable us to reach a situation whereby Iran's nuclear capabilities are destroyed without the possibility of recovery," Giora Eiland told a conference at Tel Aviv University.
Military strikes and aerial attacks cannot force Iran to surrender or give up its nuclear program, said Eiland, pointing out that Israel "cannot defeat Iran".
Israel and its close ally the United States accuse Iran of seeking a nuclear weapon, while they have never presented any corroborative document to substantiate their allegations. Both Washington and Tel Aviv possess advanced weapons of mass destruction, including nuclear warheads.
Iranian officials have repeatedly stressed that the country's nuclear activities are for peaceful purposes only. They have even stated that Tehran has no intention to launch a military attack against Israel.
Israeli officials regularly threaten Iran with a military attack on the bases of their allegations.
During the conference, Eiland also warned of the dire consequences of carrying out an unsuccessful strike against the country.
"If you undertake a failed military operation, you pay three-fold: firstly, you didn't succeed in hitting what you wanted, secondly, you've hurt your deterrence capabilities, and thirdly, you're perceived as the aggressor," he said.
"Iran is not Iraq of 1981 and not even Syria of 2007. It is likely that an attack on Iran would garner a widespread response not merely by Iran, but also other nations in the region," he cautioned.
An Iranian retaliation following an attack would endanger Israeli and American interests in the region, warned Eiland.
The former Israeli general also said that Tel Aviv must coordinate its strategies with Washington to carry out a military strike against Iran, as it does when attacking the Gaza Strip.
"It is completely clear that if an Israeli operation in Gaza requires certain level of coordination with the US, this is certainly the case with an operation in Iran, where the implications beyond Israel are of course far reaching," he said.
Despite advising against military action, the Israeli war expert said that Tel Aviv's opportunity to attack Iran is "short-lived", adding that a possible strike would be feasible for a two year period, beginning in the summer of 2009.
Speculation that Israel could bomb Iran has mounted since a big Israeli air drill in June. In the first week of June, 100 Israeli F-16 and F-15 fighters reportedly took part in an exercise over the eastern Mediterranean and Greece, which was interpreted as a dress rehearsal for a possible attack on Iran's nuclear installations.
Iran has, in return, warned that it would target Israel and its worldwide interests in case it comes under attack by the Tel Aviv.
A US attack on the Syrian village of Sukkariyah on October 26, has also raised speculation about the likelihood of a US unilateral strike on the Islamic Republic.
The United States has also always stressed that military action is a main option for the White House to deter Iran's progress in the field of nuclear technology.
Iran has warned it could close the strategic Strait of Hormoz if it became the target of a military attack over its nuclear program.
Strait of Hormoz, the entrance to the strategic Persian Gulf waterway, is a major oil shipping route.
Meantime, a recent study by the Institute for Science and International Security (ISIS), a prestigious American think tank, has found that a military strike on Iran's nuclear facilities "is unlikely" to delay the country's program.
The ISIS study also cautioned that an attack against Iran would backfire by compelling the country to acquire nuclear weaponry.
Intensified threats by Tel Aviv and Washington of military action against Iran contradict a recent report by 16 US intelligence bodies which endorsed the civilian nature of Iran's nuclear plans and activities.
Following the US National Intelligence Estimate (NIE) and similar reports by the IAEA head - one in November and the other one in February - which praised Iran's truthfulness about key aspects of its past nuclear activities and announced settlement of outstanding issues with Tehran, any effort to impose further sanctions or launch military attack on Iran seems to be completely irrational.
The February report by the UN nuclear watchdog, the International Atomic Energy Agency, praised Iran's cooperation in clearing up all of the past questions over its nuclear program, vindicating Iran's nuclear program and leaving no justification for any new UN sanctions.
The UN nuclear watchdog has also carried out at least 14 surprise inspections of Iran's nuclear sites so far, but found nothing to support West's allegations.
Following the said reports by the US and international bodies, many world states have called the UN Security Council pressure against Tehran unjustified, demanding that Iran's case be normalized and returned from the UNSC to the IAEA.