His comments came as the US shifted closer to giving assistance, but signalled that it still has reservations over supplying weapons to overthrow Saddam Hussein.
There is strong congressional pressure for military aid, but resistance from the White House, the CIA and other Middle Eastern governments.
"I do not think it's time to provide AK-47s and armed groups and other things," General Anthony Zinni told the Royal United Services Institute in London. "Not one single leader or person I've met in the region supports arming external opposition groups, not one. And without regional support, I don't know how you could make it happen."
The United States has a poor track record in covert action, and arming the Iraqi opposition might just amount to "rolling the dice" in an explosive region, he said.
America has been seeking a regional base for the opposition to play a role but has received a cold response.
Six of the leading opposition groups - including the two main Kurdish groups, the KDP and the PUK, and the Iraqi National Accord - are holding meetings in Washington this week with the State Department, Congress and the White House.
Madeleine Albright, the US Secretary of State, said on Monday that America would begin the flow of aid later this year, but it would not at this stage include weapons. The Iraq Liberation Act allows the US administration to provide up to $95m (pounds 60m) in aid for the overthrow of the regime in Baghdad, including military supplies and assistance. But for the moment, America is only providing non-lethal assistance, such as computers and help in setting up offices in the US, London and the Middle East.
"We're not prepared to take action that is premature or that puts people's lives needlessly at risk," said James Rubin of the State Department.Reuse content