Israel is becoming increasingly concerned over what it perceives as a subtle drift in American policy statements that may be encouraging the Arabs to believe that they can insist on more concessions than an elected Israeli government can deliver.

Recent statements by the Carter administration about Palestinians and borders have usually been explained away later by State Department spokesmen in terms that are compatible with Israel's basic position, and there is no doubt here about the administration's commitment to Israel's security.

There is a growing worry, however, tha tambiguous statements, whether planned or unplanned, are creating a climate of psychological pressure on Israel and a climate of illusion in the Arab world that could lead to difficulties for Israel and the Arabs when negotiations begin.

Acting Prime Minister Shimon Peres, presiding over his first Cabinet session yesterday, turned down proposals that the government conduct a review of U.S.-Israelis relations. Peres, who became acting prime minister Friday following Yitzhak Rabin's decision to take a leave because of his involvement in a financial scandal, decided that any Cabinet debate on relations with the United States by a caretaker administration three weeks before a general election would be inappropriate.

Even so, Foreign Minister Yigal Allon told the Cabinet that, American denials not withstanding, there could be no hiding the possibility that serious differences exist between the United States and Israel on "questions of primary importance," the official communique said.

Specifically, Allon was commenting on recent press reports from Egypt saying that the Americans had discussed with the Egyptians a plan under which Israel would return to 1967 borders, and early warning stations, such as the ones now operating in the Sinai, would be placed outside the final borders of Israel.

American diplomats have assured the Israelis that they were merely exploring possibilities rather than discussing a formal American plan. For the Israelis, however, "defensible borders" means the retention of large pieces of the occupied territories. Allon told the Cabinet that "no technical means or other security arrangements" could be considered a substitute for defensible borders, but only as supplementing them.

The Israeli government and a majority of the people are opposed to a return to 1967 borders. Israel's euphoria when Carter used the term "defensible borders" during Rabin's recent visit to Washington was quickly dashed when American officials explaned that the president was talking only of "monor adjustments" to the boundary line.

Conversely, Israel does not want the United States to lead the Arabs to think that a return to 1967 borders can be imposed on Israel fearing that this will only encourage the hardliners and discourage the moderates in the Arab ranks. Israel insists that the final borders should come as a result of negotiations with the Arabs, not as the result of an imposed plan.

President Carter's recent use of word "homeland" in referring to the Palestinians, which so upset the Israelis, was explained away in terms of American preference for a Palestininan state as part of Jordan, which Israel favors. Israel fears, however, that the U.S. position was stated only as a preference while Israel's firm policy is that there should be no third state between it and Jordan.

Recent statements by Egyptian leaders have said that the United States was changing its position in favor of a Palestinian state on the West Bank and Gaza and these statements have also worried Israelis.

The State Department repeated its position that a solution to the Palestinian problem was only one of three main concerns - the nature of a final peace - but the Israelis fear that too many American statements on the matter have left the door open to too many differing interpretations.

This may indeed be the American intention, but the Israeli view is that, no matter how many clarifications are issued later the United States is running the danger of creating "an illusion in the Arab world that will make it more difficult for all concerned when it comes time to negotiate," one official said.

The Israelis feel that some progress toward peace must be made at the Geneva Conference on the Middle East if the momentum is to continue. If the Arabs expect too much from the reconvening of a Geneva convention, the resulting disappointment will become all the more politically and emotionally dangerous, thus increasing the chances of another war, the Israelis believe.

The concept of giving up tangible territory for intangible promises is still one that disturbs Israel. A case in point came last week when the last known Israeli dead from the 1973 war were exchanged for 47 Arabs prisoners held in Israel. The Israelis remember former Secretary of State Henry Kissinger telling them three years ago that Egypt had promised to return all war dead without delay. The Egyptians also promised to tone down the propaganda war against Israel as part of the Sinai agreement, yet this has not happened. The Americans, according to the Israelis, admit that the Egyptians have not lived up to their part of the bargain, but excuse it because of changing political circumstances.

As for peres, sources close to him say that he is very much aware of the importance and necessity of Israel's relations with the United States and that he will try to improve that relationship. Peres was gratified that President Carter spoke well of him after the Labor Party chose him to replace Rabin and he is confident that he can get along well with the Carter administration.

There is a vague feeling here that Rabin's visit to the United States in March did not go as well as had been hoped and the expectation is that Carter will want to meet the new Israeli prime minister following next month's elections. The odds are that Labor will win and that Peres will be asked to form the next government.

Sources say that Peres is well aware that Israel has for too long presented the image of a weak and drifting leadership, lamely being able to form a cohesive and clear policy of its own. He can be expected to try to change that image and to restore confidence in Israeli's ability to enter into meaningful negotiations.