Two Democratic senators, in a move designed to restrain U.S. commitments in Central America, proposed yesterday to require congressional approval of all U.S. military operations, even covert ones, in that region.

Sens. Christopher J. Dodd (Conn.) and Paul E. Tsongas (Mass.) said they are not sure how to draft legislation giving Congress control over covert actions but said they will propose a new mechanism to do so next week.

Yesterday's proposal was prompted in part by news reports this week that the Reagan administration has authorized a covert operation against the Sandinista government of Nicaragua. Dodd said he has independent reasons for believing the reports.

Their broad-gauge plan would require specific congressional authorization of any military or economic operations in Central America and would significantly limit the administration's maneuvering room in countries such as El Salvador, Guatemala and Nicaragua.

It would require explicit congressional authorization for dispatch of any combat troops or training personnel. Under the War Powers Act, a president may send troops abroad for 60 days without congressional approval.

It would also prevent the president from unilaterally using special discretionary funds for existing defense stockpiles and from reprogramming foreign aid funds for use in that region.

Tsongas said he is motivated by a "fear that the United States is on the verge of a 1950s interventionist policy" in Central America, such as the one that culminated in the overthrow of the Guatemalan government of Jacobo Arbenz.

Covert actions, under present law, must be reported to the Intelligence committees of both houses. The two senators said they are considering broadening that requirement to include the Appropriations and Foreign Affairs committees.