Senior members of the House Foreign Affairs Committee have asked the Carter administration to consider new "security support" for Pakistan, including supplying conventional arms, in an effort to stop that country's drive to build nuclear weapons.

Chairman Clement J. Zablocki (D-Wis.) and four high-ranking Democratic and Republican committee members made the proposal late last week in a letter to Secretary of State Cyrus R. Vance. The lawmakers expressed "deep concern" that atomic weapons capability for Pakistan could lead to a nuclear arms competition and ultimately a nuclear war on the Indian continent and also could "profoundly destablize" the Persian Gulf and Middle East.

Moving in the opposite direction from the security inducements the congressmen suggested, the United States cut off military and economic assistance to Pakistan in April after verifying reports of a secret uranium enrichment plant aimed at producing atomic weapons.The cutoff of funds was required by a 1976 law, generated by members of Congress, that was intended to fight nuclear proliferation.

State Department officials have expressed no doubt that Pakistan is seeking atomic weapons capability through two, possibly three, programs. However, the officials have expressed considerable doubt that either the cutoff of aid or an offer of conventional weapons will persuade Pakistan to abandon its drive.

In an earlier phase of Pakistan's nuclear drive, the United States suspended aid commitments for more than a year, from September 1977 until October 1978, because the Islamabad government had contracted to import from France a nuclear reprocessing plant capable of making weapons-grade plutonium. The United States agreed to resume aid and weapons sales last October after the French government backed out of the contract.

During the brief period between the lifting of U.S. aid sanctions late last year and their reimposition this spring, the United States offered to supply F5 fighters to Pakistan. State Department officials said no nuclear strings were attached to the offer, made in Islamabad last November by Undersecretary of State Lucy W. Benson.

Pakistan has shown no interest in the F5, which it considers not powerful enough to meet its long-term military needs or the competition from India next door. The Pakistanis reportedly contracted recently for 32 Mirage jets from France.

An interagency committee of Carter administration officials is considering diplomatic approaches to the Pakistani A-bomb problem, which is believed to present a serious risk of nuclear proliferation with worrisome regional effects and possible worldwide effects on countries without nuclear weapons.

In their letter to Vance, the House members did not back away from applying aid sanctions, saying that "still sterner measures" may be necessary in the future to demonstrate to other nations that "the political costs of going nuclear are high." The lawmakers added that "sanctions alone, however, are unlikely to provide a sure or ommediate solution to the current problem."

The letter recommended that the United States "understand and more effectively treat Pakistan's underlying security concerns" to alleviate the need for an atomic weapons defense. The lawmakers did not say in detail how the United States should "bolster Pakistan's sense of self-security in the face of new and compelling dangers," but they strongly hinted that arms sales are part of the answer.

Zablocki said in an interview that arms sales on credit might be undertaken, despite the sanctions of the antiproliferation law, through a presidential waiver or some other legal device. Rep. Paul Findley (R.-Ill.), another signer of the letter, said Congress probably would have to amend the antiproliferation act.

"It would be unwarranted for critics to characterize any such initiative as a stark trade of conventional arms in return for a freeze on nuclear weapons work - although as to the relative danger of the two we cannot see how there can be much room for doubt," the letter said. It expressed the hope that U.S. assistance and reassurance would be seen "as a modulated response to disturbing new regional developments" rather than as a buyoff plan.

The lawmakers listed as threats to Pakistan: secessionist activity in several frontier regions, growing Soviet involvement in neighboring Afghanistan, disappearance of the security assurances once provided by the shah of Iran, disintegration of the U.S.-sponsored CENTO alliance in the region and India's 1974 nuclear explosion and recent purchases of advanced attack aircraft.

The lawmakers' mention of potential "destabilization" of the Middle East was an apparent reference to unconfirmed reports that the Pakistani nuclear drive is being financed by Libya and possibly other Arab countries, and that it will produce an "Islamic bomb" in opposition to Israel's reported nuclear arsenal.

U.S. officials have expressed doubt that Pakistan has received outside financing in its a-bomb efforts, and Pakistan has denied having such financing in its A-bomb efforts, and that it is engaged in a nuclear program but has insisted that it is entirely peaceful.

In addition to Zablocki and Findley, signers of the letter to Vance were Re. William S. Broomfield (Mich.), ranking GOP member of the committee; Rep. Jonathan B. Bingham (D-N.y.), chairman of the international economic policy subcommittee, and Rep. Lee H. Hamilton (D-Ind.), chairman of the subcommittee on Europe and the Middle East.