WASHINGTON (AP) _ U.S. strategy in the Persian Gulf should aim at keeping Iran from spreading its Islamic fundamentalist revolution to the Arab world, even if military force must be used, a key Democratic legislator said Tuesday.

''The danger of the Iranian revolution is its focus on destabilizing the Islamic world in general and the neighboring Arab states in particular,'' said Rep. Les Aspin, D-Wis., chairman of the House Armed Services Committee.

Aspin has been critical of President Reagan's plan of reflagging 11 Kuwaiti tankers and protecting them with Navy convoys in the war-torn Persian Gulf. He renewed that criticism Tuesday in a speech to the National Women's Democratic Club.

''We need to work toward a plan to end the escorting and reflagging on our timetable and on our terms,'' he said.

But speaking to the larger issue of the long Iran-Iraq war, he said the ''basic and fundamental question'' for the region is the threat posed by Iran's fundamentalist regime to gulf Arab nations such as Bahrain, Kuwaiti and Oman.

The United States can't ignore or suppress the Iranian revolution, he said, but ''we can contain it.''

''And that is the strategy we should follow for dealing with the Islamic republic of Iran,'' he said. ''Containment can't work for centuries, but it can work for years.''

He said the challenge is ''to mobilize the world behind such a strategy, and to convince Iran that the world is not about to allow the Iranians to export their revolution by force or subversion.''

A world effort would have to include the Soviet Union, he said, however unpleasant that might be.

''For long-range policy objectives in the gulf, we need to face up to the necessity of bringing the Soviets in, not as a special player, but as one in a group of players.''

To support his containment policy, Aspin proposed using a number of ''sticks,'' including an arms embargo and military force.

''The trick is to apply the appropriate amount of force at the appropriate time,'' he said. ''The tactic of imposing force at the point of the crime - as with the (Iranian) mine-laying ships and last week's speedboat attacks - is a rational use of force.

''Bombing cities is a bad idea. A discriminating use of force is an important part of a containment strategy. Indiscriminate use of force just creates more martyrs for their cause.''

He also said Reagan should invoke the War Powers Act, which would mean that Congress would have to vote within 60 days whether to support or oppose Reagan's gulf policy. Reagan has refused to invoke the 1973 law, arguing that it does not apply to the current situation.

If there was a congressional vote on the policy, Aspin said, neither the Senate nor the House would vote to pull the forces out of the gulf. ''Such a vote would strengthen the president's hand immensely,'' he said.

Senate Democratic leaders are seeking support for a resolution that would require some type of congressional vote early next year on Reagan's policy.