The Carter administration yesterday called the Arab world's economic boycott of Egypt "negative and unhelpful," but administration officials carefylly refrained of such key Arab nations as Saudi Arabia and Jordan.

Instead, State Department spokesman Hodding Carter said the United States plan to take "careful soundings" about the intentions of individual Arab governments before reaching any conclusions or policy decisions about the potential effects of the boycott on the Middle East peace process.

This cautious U.S. approach was outlined by Carter following the decision Saturday in Baghdad of 19 Arab countries to impose a total economic embargo on Egypt in retaliation for President Anwar Sadat's signing of a peace treaty with Israel.

The Baghdad decisions, which also called for participating governments to break diplomatic relations with Egypt, could, if implemented strictly, totally isolate Egypt from the Arab world and cause severe economic difficulties for Sadat.

Saudi Arabia and Kuwait have contributed almost $300 million in cash to Egypt annually and millions more in other forms of aid. The Saudis also are supposed to underwrite in the $525 million sale of 50 American F5 jet fighters to Egypt.

For that reason, the acquiesence in the Baghdad decisions of Sadui Arabia and Jordan, another potentially key player in the drive for a compreshensive Middle East peace settlement, is known to have disappointed U.S. policymakers. Two weeks ago, a highlevel administration team that included President Carter's national security affairs adviser, Zbigniew Brzezinski, visited both countries to urge that they take a moderate stance at the Baghdad meeting.

That disappointment was reflected in yesterday's statement by Hodding Carter calling the Baghdad results "negative and unhelpful" and noting that none of the Arab states "has proposed anything that has any prospect" of solving the Middle East problem.

However, the spokesman also pointed out that, until detailed diplomatic consultations with various Arab governments have been concluded.