The Carter administration, following a trip by two of its highest officials to the area, has deferred the once-urgent program of military and economic aid to Pakistan. Officials said congressional action on the plan is now unlikely before summer, at the earliest.

According to officials familiar with the just-completed mission of presidential national security affairs adviser Zbigniew Brzezinski and Deputy Secretary of State Warren Christopher, the delay in moving forward with the aid plan is at the request of the Pakistanis.

The aid program is "not quite so urgent" as it was before the Brzezinski-Christopher trip, said a White House source. Officials said Pakistan's President Mohammed Zia ul-Haq made clear to his American visitors that he wants no action taken here without his further approval.

U.S. officials took the position yesterday that the reassurances to Zia from Brzezinski and Christopher, along with statements by President Carter, have satisfied the Pakistani leader regarding U.S. determination to defend his country against any military threat from Soviet-ruled Afghanistan on Pakistan's western border.

Since Zia now is satisfied with U.S. determination, these officials said, the need to move quickly with congressionally-approved evidence of American concern is no longer a consideration.

A U.S. military team that remained in Pakistan will recommend the specific makeup of $200 million in U.S. military aid that has been offered Pakistan over a two-year period. The United States also has offered $200 million in economic aid. Despite criticism from Zia that the sums are "peanuts," the United States has refused to up the ante under present circumstances.

Failure to obtain a go-ahead from Zia on the $400 million package in the next several weeks will produce a more complicated legislative situation in Congress because of the effect of budget authorizations.

Because no word from Zia is expected quickly, officials said, the Pakistan aid program is unlikely to become law before summer.

Special congressional authorization of any Pakistan aid program is essential because military and economic assistance is now barred by law, due to Pakistan's continuing efforts to build an enriched uranium plant capable of making nuclear weapons material. The aid cutoff was announced last April because of the application of U.S. laws that seek to curb the spread of nuclear weapons.

Brzezinski, who returned from Pakistan and Saudi Arabia Tuesday, submitted an informal as well as a written report on his mission to Carter yesterday.

Carter also met with former secretary of defense Clark M. Clifford, who headed a parallel mission to India, Pakistan's rival and neighbor. Carter thanked Clifford for "a very successful and a fruitful mission."

Carter made no public criticism of Clifford's controversial statement in New Delhi that any Soviet push from Afghanistan toward the Persian Gulf "means war" with the United States. By inference, Carter seemed to endorse Clifford's statement by saying that "the clarity of the American position is crucial, not only for our friends and allies, but for those who might be tempted to use military force or aggression in the future."

On Capitol Hill, a high-ranking Navy official said U.S. forces "are stretched precariously thin" throughout the Pacific and Indian Ocean region, requiring a major buildup.

Adm. Robert L. J. Long, commander of U.S. forces in the Pacific, told the Senate Armed Services Committee that "we need more ships, more aircraft and upgraded weapons systems.

In a related development, two members of Congress protested the granting of export licenses for U.S.-made engines to power four Iraq Navy frigates. Reps. Jonathan Bingham (D-N.Y.) and Millicent Fenwick (R-N.J.) objected to the sale because Iraq has been listed as a country that supports international terrorism.

Donald A. Furtado, deputy undersecretary of commerce, said the licenses had been properly granted but that a review will be conducted before the engines are shipped.