President Carter announced a six-point yesterday aimed at restricting American arms sales overseas but retained for himself broad discretionary power to grant exceptions to the new rules.

The policy, a sharp departure from past pratices that have seen the volume of U.S. arms sales rise annually, would for the first time impose "a presumption against an arms sale," according to Jessica Tuchman, a member of the National Security Council staff, who outlined the plan at the White Hosue yesterday.

"This places the burden of proof on those arguing for a sale," she said. "That is the basic, central core of the policy."

Declaring that as the worll's largest arms supplier the United States bears "special responsibilities" to curb the international traffic in arms, the President said in a statement.

"I have concluded that the United States will henceforth view arms transfers as an exceptional foreign policy implement, to be used only in instances where it can be clearly demonstrated that the transfer contributues to our national security interests.

"We will continue to utilize arms transfers to promote our security and the security of our close friends. But in the future, the burden of persuasion will be on those who favor a particular arms sale rather than those who oppose it."

How well the new policy works in pratic is likely to depend largely on the extent to which Carter exercises his authority to grant exceptions to it.

In his statement, the President said the restrictions would not apply to arms transfers to nations that have "major defense treaties" with the United States, naming specifically the North Atlantic Treaty Organization countries of Western Europe, and Japan, Ausralia and New Zealand in the Far East.

He also reiterated his commitment to "honor our historic responsibilities to assure the security of the state of Israel."

But Carter added to these two broad exceptions to the restrictions: cases involving "extraordinary circustancts," which he would define, and cases "where I determine that countries friendly to the United States must depend on advanced weaponry to offset quantitative and other disadvantages in order to maintain a regional balance."

The policy, Tuchman said, "is designed to allow the President flexiblity. The President indicated he wants to make these decision himslef."

In the first of the six points he announced, Carter pledged his administration to reducing the amount of arms transfer commitments made during the fiscal year that begins Oct. 1 below the amount made during the current fiscal year. The latest estimate is that arms sales will total $8,8 billion this fiscal year, but Tuchman said this is only a rough guess and that the amount could reach $10 billion. An earlier plan to announce a fund ceiling on future arms sales was dropped.

The other five points state that:

The United States will not be the first supplier of new, advanced weapons to any region of the world shere they would "create a new or significantly higher combat capability."

Development or significant modification of advanced weapons systems solely for export is prohibited.

Agreements for the coproduction of "significant weapons and equipment" - under which United States supplies other nations with the plans and technology to build American-designed weapons - are prohibited.

As a condition of new arms sales contracts, the United States may prohibit recipient nations from reselling the weapons to a third nation. Under existing policy, the resale of American weapons requires the U.S. approval, which has frequently been granted.

State Department approval will be required for any actions by government agents or private manufacturers that might promote the sale of arms abroad.

There is already an exception to the ban on coproduction of significant weapons. Citing the United States' "special relationship" with Israel, the President last week agreed to include Israel among the nations allowed to build the F-10 fighter plane.

In his statement, Carter said that curbing the international arms traffic will require the cooperation of other major amrs suppliers, including the Soviet Union. He said U.S. representatives plan to meet with officials of these other nations to discuss possible multilateral measures.