Pakistan wants the Reagan administration to give it economic aid and the right to buy U.S. weapons at cut-rate prices, but no direct military assistance, according to Foreign Minister Agha Shahi.

By not accepting direct U.S. arms aid, Shahi said, Pakistan hopes to avoid being labeled a tool of Washington. He spoke in an interview shortly before he and President Mohammed Zia ul-Haq met last night for the second time in eight days with U.S. Ambassador Arthur W. Hammell Jr. to discuss what appears to be the Reagan administration's keen interest in revitalizing once-close ties between the two nations.

The results of those discussions, if any, were not known. But in the interview, Shahi said Pakistan has pulled back from its demand of last year that the United States convert its 1959 security agreement into a full-fledged treaty, fearing a bruising Senate ratification battle.

Furthermore, he repeatedly emphasized that any arms that America allows Pakistan to buy with money from "our friends" -- presumably its Islamic brothers of the rich Persian Gulf oil states, especially Saudi Arabia -- would not be used against neighboring India.

Instead, he added, they would be used for bolstering the "self-confidence" of Pakistan, which has to operate under the shadow of 85,000 Soviet troops sitting in Afghanistan on the other side of its northwestern frontiers.

Shahi spoke somberly about the possibility of improved U.S.-Pakistani relations despite the signs from Washington that the Reagan administration considers Islamabad a key link in its plans for strengthening security in the Persian Gulf.

These signs include official statements that the United States is giving special consideration to Pakistanian's needs and Secretary of State Alexander M. Haig Jr.'s declared opposition to laws that bar American aid to countries, such as Pakistan, that are believed to have nuclear weapons programs.

Instead of welcoming this changed attitude in Washington, as other Pakistani officials and diplomats have, Shahi opened the interview by bringing up anti-Pakistan newspaper columns and congressional statements. He said Pakistan is "frankly worried" whether "the administration can sustain its policies in the face of congressional criticism."

He did say, however, that improved U.S.-Pakistani relations could benefit Washington, Islamabad and the world. There was no word here on the administration's specific thinking on aid to Pakistan, although it appeared likely that Zia's marital-law government will get a far bigger bundle from the more sympathetic Reagan administration than the $400 million offer from Jimmy Carter that was rejected as "peanuts" one year ago.

Pakistani sources talk about more than $2 billion in aid needed to revitalize this country's antiquated armed forces. Some well-informed U.S. analysts expect an aid package of perhaps half that spread over two or three years, despite Shahi's declaration that Pakistan is not in the market for U.S. arms financing.

American diplomats here and in Washington have been keeping unusually mum on the administration's proposals. This is mainly because they believe the United States lost a chance last year to improve relations with Pakistan because most of its plans appeared in the press before they were told to Zia's government.

"The whole area has to be handled with great skill," commented one non-American Western diplomat with long experience in the region. "If Reagan tries to force anything too obviously on Pakistan he will get a repetition of Carter. I fear Reagan will make a new offer to Pakistan and get it thrown back in his face."

Pakistan is eager to retain its position in the nonaligned movement and the Islamic world, and it fears this position could be jeopardized by the appearance of too close a relationship with the United States.

Nonetheless, Pakistan's own aid needs are immense and, if centered in the Northwest Frontier and Baluchistan -- the two provinces bordering Afghanistan -- the aid could be considered security-related.

In the military sphere, Pakistani sources say unofficially that any military aid money would likely go for new jet fighters, modern tanks and antitank missiles and a sophicated air defense system for the border with Afghanistan.

Most present Pakistani equipment is American. But Islamabad is barred from making more purchases because of its nuclear program, which despite strong denials by the Zia government is believed by U.S. experts to be aimed at building atomic weapons. Even if the Reagan administration persuades Congress to lift the arms ban, there remains the question of which "friends" will supply Pakistan with the cash.

The controlled Pakistani press carried a story earlier this month suggesting that Saudi Arabia would pick up the tab for arms purchases from the United States and other Western sources. But the Saudi aid for military equipment has never materialized, according to diplomatic sources here.

In the interview, Shahi brought a new idea into the discussion: the request for cut-rate prices for arms purchased for Pakistan by its friends. He said he felt it would be appropriate for the Reagan administration to allow it to buy arms on the same terms the Soviet Union agreed to sell weapons to India, where a $1.6 billion price will bring more than $6 billion worth of weapons.

That type of deal, Shahi said, would be "defensible and quite compatible" with Pakistan's nonaligned status. In fact, it appeared that he was saying that if India can get such a good deal from Moscow, Pakistan should get the same from Washington.

The review process process on this and other questions is going on in Washington, where one diplomat said, "It's like peeling an onion." Hummell has been deeply involved, returning here 10 days ago after more than a month of consultations in Washington.

The notion of strenghening America's ties with Pakistan has led to other questions that have bedeviled the State Department experts and Reagan appointees alike:

What about lack of public support for Zia's authoritarian, unrepresentative military government? Does its fragility mean the United States will be perceived as propping up another shah? What about human rights violations and the jailing currently of at least 500 politicians seeking elections? How will arming Pakistan affect America's relations with India, the larger nation to the south? And will allowing Pakistan to buy arms undercut America's stand against nuclear proliferation?

At least one of those questions appears to have been decided in Pakistan's favor, and that decision is believed to have been conveyed to Zia. According to well-informed diplomats, the United States, while continuing to try to keep good relations with India, will not allow New Delhi's opposition to control the amount and type of aid Pakistan will get.