Iran's Islamic-inspired government, which has shifted the country from discreet friendship with Israel to open hostility, has pushed high up on the Camp David agenda new Israeli insistence on Gulf of Suez oil guarantees and increased military aid from the United States.

The Israeli determination to give increased emphasis to these concerns is based partly on the premise that since the number of pro-Western governments in the Middle East is declining, Israel's value as a stabilizing force in the region should rise in the eyes of Americans.

It also stems in part from a growing feeling here that Iran has shown U.S. policy in this part of the world to be unreliable, and that Israel should begin counting on itself more and hold onto the Sinai for security reasons.

Israeli officials are reluctant to discuss specifics of the new demands, for fear of upsetting the delicate talks between Israeli Foreign Minister Moshe Dayan and Egyptian Prime Minister Mustapha Khalil. But it is known that before leaving for Washington, Dayan received detailed instructions from Prime Minister Menachem Begin to impress upon the United States and Egypt the changed conditions in the region since the negotiating teams last met.

Begin, in a closed-door briefing this week to the Knesset's foreign affairs and defense committee, alluded to the new peace talks topics and promised the committee a full report when the Israeli delegation returns this weekend for consultations with the Cabinet.

The committee, in turn, approved a resolution stating that "Israel will not be able to live up to the agreement and evacuate the Sinai within three years, while at the same time assuring minimal military preparedness essential to its security, without getting special and comprehensive aid from the United States."

The upheaval in Iran also has intensified extreme right-wing pressure on Begin never to give up the Sinai in exchange for a peace treaty with Egypt, because of the uncertainty of Israel's future oil supply.

Iran had been supplying Israel with slightly more than half the 54.7 million barrels of oil it consumes annually. The tap was turned off even before Ayatollah Ruhollah Khomeini returned to Iran from exile. Now his new government has flatly said it will never sell oil to Israel again.

Israel has turned to Mexico, which had been supplying about 10 percent of the country's needs, and to purchasing oil from other markets in spot transactions, occasionally using intermediaries. But the spot purchases usually are at a higher price that that offered by regular suppliers and, while fulfilling an immediate need, are not a practical way of buying oil over a long period.

As a result, Israel has focused its attention on the Alma oil fields in the Suez Gulf, which produce 30,000 barrels of crude daily, or about 15 percent of the country's consumption. By the end of 1979, Israel expects the Alma fields to be producing a third of the nation's needs.

The Alma fields, developed by Israel after it captured the Sinai Peninsula in the 1967 six-day war, were the object of hard bargaining by Israel immediately after the first Camp David meeting in September. In their public statements Begin and Dayan repeatedly said that access to the Alma fields was essential if Israel were to give up the Sinai.

But in the last months of 1978, the prime minister and foreign minister were conspiciously quiet about Sinai oil. When the subject was raised publicly by Energy Minister Yitzhak Modai, Dayan stressed that Israel would never let the issue stand in the way of a peace treaty with Egypt.

More recently, however, Dayan has been mentioning the Alma fields, saying that because of developments in Iran it is essential for Israel to have ironclad guarantees of access to Sinai oil. some observers say that could become a sticking point in the peace talks and could imperil or delay the outcome of this phase of the negotiations.

In spite of the importance of oil, most concern over fast-breaking developments in Iran has centered on regional strategic considerations and shifting alliances in the Persian Gulf area.

Apart from the hard-line stance taken by the far right, the mainstream of political thought here appears divided between two more moderate strategies: Move swiftly for a treaty signing with Egypt before regional instability and Islamic revivalism make peace unattainable, or proceed cautiously and slowly until all implications of the Iranian revolution are clearly understood.

Advocates of a move-swiftly policy point out that the success of the Shiite Moslem revivalism in Iran could influence the stability of other Persian Gulf countries, particularly Iraq, which has a 45 percent Shitte population, and even Saudi Arabia, which is predominantly Sunni.

Israel traditionally has relied on practical, if not always official, relations with non-Arab nations in the greater region -- Iran, Turkey, Ethiopia and occasionally East Africa -- although Ethiopia has turned against Israel and Turkey has its own trouble. This policy should now give way to expediting a treaty with Egypt, even at the price of more concessions, according to politicians who are urging Begin to act quickly.

Often, the same arguments -- presented with a different spin -- are offered by advocates of a policy of caution and deliberation.

Begin is being told by some advisers that events will lead to a hardening of the American position by bringing Egypt and Saudi Arabia closer together, and that Israel must be wary of being rushed into a pact that could later compromise its security.

They see America's strategic interest in the Middle East shifting closer to the Saudis and Egyptians out of fear that continued reliance on Israel as the principal stabilizing influence in the region will further alienate the Arab world and jeopardize oil sources. In addition, the Iran experience has devalued U.S. commitments in the eyes of some.

"As Iran has shown, the United States is no longer in a position to say to anybody, 'Trust us. We will stand behind you,'" said one Israel official. He added, "In the case of Israel, we may think differently today than we did six or eight months ago."

Another official suggested that what Israel may have accepted from the United States verbally six months ago, it may now ask for in writing as a treaty amendment. However, he added wryly, "That may give us about as much comfort as Nationalist China."

Fears stemming from the Iraqi-Syrian attempts to confederate -- or at least form a military union -- have been compounded by the possibility that Iran may join the alliance and drastically alter the balance of power in the region.

Equally disquieting to Israelis was the visit to Iran this week by the Palestine Liberation Organization leader, Yasser Arafat, and the new Iranian government's pledge to support the PLO struggle against Israel.

While the PLO was known to have trained and financed some guerrilla groups in the Iranian revolution, Arafat's visit to Tehran provided the first public indication that Iran may become an active military partner against Israel.

When asked if the Israeli government now considers Iran to be an enemy, a Foreign Ministry official here said, "Not until Iran proves itself such. [Dayan] is making a distinction between an open friendship between Khomeini and Arafat and aggression. But if they join forces, this will be a very grave danger."

Begin's aides have said that the Iranian crisis multiplies the importance of accompanying any treaty with firm commitments by the United States to increase financial assistance for security and keep a check on U.S. military sales to Egypt and Saudi Arabia.

"If anything, Iran has proved the danger of arming Egypt to the teeth. What if Egypt buys 200 F15s from the United States, and then someone like Khomeini overthrows Sadat," said one Begin aide, referring to Egyptian President Anwar Sadat.

He noted that the same principle applies to Saudi Arabia, which reportedly wants to buy all of Iran's F14 jet fighters, and which he said is potentially as vulnerable to Islamic-inspired unrest as Iran was.