A former Iranian vice president who is backing the opposition's challenge to the Teheran regime warned the US and Israel on Saturday against attacking Iran over its nuclear program. Ataollah Mohajerani, the Islamic republic's former vice president for parliamentary affairs, also cautioned that military force as well as sanctions would hurt the proponents of the "Green Revolution," a diverse coalition of opponents to the current regime that emerged following the flawed presidential elections in June and the ensuing crackdown on dissidents. He took an equivocal approach to the US efforts at engaging the Iranian leadership, but was categorical that the use of force would only rally the country around the current regime. "It will strengthen the government in Iran," Mohajerani, said in an address to the Washington Institute for Near East Policy. "It will crush and stop the pro-democracy movement, which will die." He said that the majority of reformers would, like himself, defend the leadership "just to protect our sovereignty." He added that when it came to the military-intelligence sector, any attack would "expand their dominance over the Iranian society." Noting his ties to opposition leader Mehdi Karoubi, one of the candidates who challenged Mahmoud Ahmadinejad in the controversial June elections, and former president Muhammad Khatami, he said neither would support an attack or use it to indict those in charge. "They're not going to say that Ahmadinejad created this problem so he will have to face it," he asserted. "No, they're not going to say that." Mohajerani argued that for the Green Movement to thrive, it needed the support of a secure middle-class economic base, and contended that sanctions being considered by the West would hurt those very people and their financial prospects. "Sanctions will rob the Iranian people of this opportunity and other people will reap the benefit from it," he said, though some opposition leaders have said that sanctions would hurt the regime more and should be supported on that basis. But according to Mohajerani, creating a long-term sustainable atmosphere for reformist efforts is key. "The Green Movement is not a 100-yard dash to determine the leader after a few seconds, it's a long marathon," he said. Because he predicted that the road to change was a long one, he said it would be "unrealistic" to expect that other countries like the United States refrain from talking to and even making deals with the current regime. Calling the Obama administration's outreach a "greeting card given from your administration to the Iranian government," he suggested that talks could "ease tensions" between the US and Iran, which he supported. But he expressed concern that what he termed the "six minus five" powers - the US, Russia, China, Britain, France and German, the so-called P5+1 who are negotiating with Iran - would take advantage of a "weak" Teheran to achieve a deal that the pro-democracy movement would later perceive as "unfair." Mohajerani, who wouldn't speak to Israeli media outlets after his speech, quoted from British Chief Rabbi Jonathan Sacks and Nobel laureate Elie Wiesel as well as referenced the tragedy of the Holocaust during his lengthy speech. "In the case of the Holocaust, even if only one Jewish child was burned or killed, that would have been a catastrophe," he said, before noting the millions exterminated. Questioned on Iran's support of terrorism in the Middle East and attempts to thwart the Israeli-Palestinian peace process, Mohajerani said that that "we should not be more Palestinian than the Palestinians â€¦ We should not be more Catholic than the pope." But pressed on Iranian-sponsored attacks on Israeli and Jewish targets, he said, "It cannot be addressed in a short conversation. It takes a longer analysis." And asked for a yes-or-no answer of whether Israel has a right to exist, he replied, "This is a very, very difficult question. Let me answer this question later."