The Israeli government's declaration that there is "no impediment" to Jewish civilians settling in the Arab city of Hebron on the occupied West Bank was criticized by the United States yesterday as "a step backward" that could seriously damage the Middle East peace process.

State Department spokesman Hodding Carter said the U.S. government is seriously concerned about the implications of the decision made by Prime Minister Menachem Begin's cabinet Sunday.

Although the Begin cabinet did not say when Jews might actually start moving into Hebron, its decision, which involves the sensitive question of Jewish settlement rights in the West Bank and Gaza Strip, could have a serious impact on the Israeli-Egytian negotiations on self-government for these areas.

The Begin government contends that Jews have the right to live anywhere in these areas. In practice, though, the approximately 100 Jewish settlements in the West Bank and Gaza have been confined to sparsely populated areas, except for one group of seven families illegally occupying a former Jewish clinic in Hebron.

The ultranationalist settlement movement, Gush Enunim (Faith Bloc), has been pressing Begin to permit Jews to settle in exclusively Arab areas of the West Bank. The pressure intensified after the recent killing of a Jewish religious student in Hebron, and the cabinet's decision has been widely viewed as a teamporizing measure aimed at easing that pressure.

For that reason, the U.S. criticism expressed yesterday appeared to be a bit more low key than past Carter administration statements on Israeli settlement policy in the disputed areas. The official U.S. position is that any Israeli settlement in the West Bank and Gaza is illegal, because these territories have been under military occupation since the 1967 Middle East war.

U.S. officials said privately that yesterday's statement was intended to put the Israelis on notice that Washington is worried about the implications of the move. But, the officials added, Washington wants to see whether the Begin government actually allows Jewish movement into Hebron before it pursues its protest more vigorously and specifically.

The question of Jewish settlements or other forms of residence in the West Bank and Gaza is one of the thorniest issues in the Egyptian-Israeli talks about the future of these areas.

For that reason, Hodding Carter called the newest Israeli move an attempt to "preestablish portions of what is yet to be nogotiated." That, he added, "is prejudicial to the negotiations."