TEHRAN, AUG. 18 -- The cost of a long, grinding war with Iraq has begun to disrupt daily life in Iran, provoking grumbling in the street and increasing economic controls by the government.

Foreign reserves, strained by military purchases, have fallen as far as authorities feel is safe despite efforts to keep oil exports at profitable levels, diplomatic sources said. As a result, the imported goods that helped keep Iranians comfortable through nearly seven years of warfare have become scarcer and risen dramatically in price, hitting hard at living standards of the poor families most attached to the revolutionary Islamic government.

Against this background, Iranian leaders repeatedly have emphasized that Persian Gulf shipping lanes must be kept open for passage of tankers carrying Iranian oil. Unlike Iraq, which has pipelines through Turkey, Iran depends entirely on ships through the gulf to export its daily output of 1.15 million barrels of petroleum, which traditionally accounts for more than 90 percent of foreign exchange earnings.

The sharpest impression greeting a visitor returning to Tehran for the first time since the war began has been the apparent plenty. Shop windows have stayed full. Drivers have maintained a flood of traffic that keeps the city's streets clogged. Utilities such as telephones and electricity have kept pace with growth in the suburbs.

But after seven years of guns and butter, according to diplomats posted here, the butter has finally started to run out.

Wartime rationing, for example, has imposed a limit of one kilogram (2.2 pounds)of imported West German butter per month for a family of four. At the official rate of exchange, that much butter costs about $5 under government price controls. The black market exchange rate is seven or eight times higher, Tehran residents said, but so is the black market price of butter.

Similarly, one gallon of gasoline has risen to about $2 at the official rate whereas on the black market, taxi drivers complained, it costs twice that. With a rationing limit of 15 gallons a month, they added, private car owners and taxi drivers alike are forced into the black market to stay on the road.

Ayatollah Ruhollah Khomeini's Islamic government, in apparent recognition of the growing hardship, handed out basic necessities such as rice and meat to celebrate the Iranian new year this spring, instead of the gold coin that had been the traditional official gift, a diplomat pointed out.

Perhaps more important, Khomeini intervened directly and publicly to impose increased control over prices and hoarding last June. To do so he reversed a ruling by the Council of Guardians, a body of clerical jurists, who had decided earlier that Parliament's laws setting up the controls were unwise.

An experienced analyst here pointed out that this was the first time Khomeini made a decision on such day-to-day affairs for his government. The ayatollah, revered as the source of the revolution and its infallible guide, traditionally has limited himself to setting broad outlines and picking top officials in the government, the analyst said.

His countermanding of the Council of Guardians ruling was taken as a sign of concern that the government should move more forcefully to restrain price rises and protect the poor, the "deprived ones" who have been a mainstay of support for Iran's Islamic revolutionary revival. With Khomeini's example apparently in mind, the Supreme Economic Council announced necessary price increases this week, but also emphasized its efforts to keep prices down and combat "hoarders and profiteers."

The newspaper Jomhuri Islami, Tehran's largest daily, also took Khomeini's cue in an editorial today, saying: "Experience has shown that resistance of the executive and judicial authority before the clamors of the profiteers, bloodsuckers and plunderers of public wealth is easy, practicable and useful."

Despite the declaration, Iranians have begun to complain openly of economic trouble. A bazaar merchant lamented that sugar used to cost about 10 cents a pound but now goes for more than $2 on the black market. Meat has risen by 300 percent since the 1979 revolution, he said.

A laborer, looking at a freezerful of unappetizing small fish in a Tehran supermarket, recalled the days when he ate fresh sturgeon from the Caspian Sea. Spreading his arms wide, he smiled. "Like this they were," he said.

Diplomats said the economic pinch has been felt less in the countryside, where vegetables are grown and discontent is less apparent. In addition, they cautioned, the complaints in Tehran about hardship should not automatically be understood as opposition to Khomeini's rule.

"One should realize and accept the fact that the great majority of the people stand behind the system," said an experienced analyst.