ISLAMABAD, PAKISTAN, May 29.-The troubles that have shaken Pakistan recently are being compounded by a general souring of life-giving economic and diplomatic relations with the United States.

American aid, amounting to more than $4 billion has brought about the beginnings of a "green revolution" in both East and West Pakistan, introducing new high-yield strains of wheat and rice to fight nearly unbearable population pressures.

In West Pakistan, Western aid, mainly from the United States, is helping build a canal system greater in extent than the Panama and Suez Canals. This vast irrigation and power system will include the two largest dams in the world, scheduled for completion in 1976. In the East, among many other projects, American aid is helping to build a 2,300-mile dike to protect low-lying paddy lands from the tides and storms of the Bay of Bengal,

SITUATION CHANGED IN MARCH

Over the years American aid has been heavily committed to health, education, industrial development and every other phase of development in Pakistan, as well as sustaining the nation's budget and currency.

But on March 25 a national army made up mostly of West Pakistanis stormed into East Pakistan to crush the Bengali separatist movement. Since then, Western countries have heaped criticism on the Government in Islamabad for its policies and its heavyhanded tactics in East Pakistan.

In addition to the criticism there has been a curtailment of foreign aid that will have serious repercussions.

"We feel hedged in on ail sides by our fair-weather friends in the West," one Pakistani said. "Thank God for real allies, especially the Arab lands and People's China."

But the Arabs themselves depend on foreign aid and China has yet to demonstrate ability or willingness to fill the vacuum. Government communiqués here glowingly praised recent Chinese commodity loans and the arrival of a planeload of powdered milk in East Pakistan from Peking, but such assistance falls far short of real requirements.

RELIEF ADD GOES ON

The United States has not discontinued relief aid in the form of food and emergency supplies to East Pakistan, although shipping has been almost impossible because of disrupted communications.

Neither is the United States likely to terminate assistance to partly-finished projects such as the Indus River basin irrigation and power plant; too much already has been invested to let such projects fall by the wayside, some officials say.

But American and other Western aid is under close review and even continuation of major building projects is strongly criticized in some quarters.

An American technical expert said: "We may not be able to change Pakistan's internal policies, but we don't have to go on supporting them, especially in the teeth of what has happened in East Pakistan. Why should we continue any aid at all?"

This line of thinking is not shared by top American officials, who generally feel that some midway point should be established between business-as-usual and a total cessation of aid.

The outstanding borderline case is a projected $80- million commodity-import loan. An American decision on the loan must be made within the next few weeks or all or part of it will be lost to Pakistan.

VITAL FOR PLANNING

The American commodity loan is a vital part of Pakistan's planning, and the national budget will have to be austerely reduced without it. Pakistan already has asked for a six-month moratorium on repayment of her foreign debts, and gloomy technical talks with missions from the International Monetary Fund and World Bank are expected soon.

All the foreign criticism has stung West Pakistanis perhaps even more than the curtailments of aid. The United States in particular has been charged with paternalism and imperialistic designs on Pakistan.

A surprisingly common view was expressed by a Western educated refinery engineer who said: "The American banks are controlled by Jews so of course Washington supports Israel against the interests of the entire Islamic world. Right now Pakistan is the target. We Pakistanis think the Germans were right in World War II."

A more moderate opinion was expressed by a high Government official.. "There are some nations which I shall not mention by name," he said, "who have no moral right to speak to us. They are taking their pound of flesh in the form of servicing our debts, tied aid which must be repaid in convertible currency and shoddy goods they sell us.

"We are ready to listen to criticism but there are limits beyond which we will not go."