Sen. Alan Cranston (D-Calif.), the Senate's majority whip, yesterday challenged political currents on Capitol Hill by calling for a $5.2 billion cut in the president's defense budget.

Such a cut, Cransion said at a press conference, "would strengthen our national security by strengthening our efforts to control inflation. In the final analysis, a nation is no stronger than its economy."

Asked about the Soviet Union's steadily expanding military forces, which many senators have cited as a reason for increasing U.S. defense spending, Cranston replied:

"We are in so much better shape than the Soviets, all factors taken into accoundt, that we should not be so paranoid . . . and succumb to a sense fo inferiority every time they say 'boo' . . . "

One of Cranston's proposed cuts is to reject the administration's $2.2 billion supplemental defense authorization for this year, which is being considered in the House and Senate Armed Services committees.

A key component is more than $200 million to accelerate development of a new MX intercontinental missile. Meeting in closed session yesterday, the Senate Armed Services Committee approved this.

The supplemental money request also includes $1.3 billion to buy back equipment ordered by Iran which the United States now expects the new Iranian government to cancel.

Other cuts Cranston proposed include dropping plans for a $1.6 billion aircraft carrier, reducing defense manpower by 25,000, compelling the Pentagon to absorb more of the costs of inflation and part of a new military pay raise.

If all these reductions are made, Cranston said, spending on NATO-related programs could still be raised by the 3 percent President Carter has proposed.