Diplomats in East Africa yesterday expressed fears that Friday's Senate vote barring the importation of Ugandan goods to the United States might imperil an estimated 200 Americans remaining in Uganda.

The diplomats said they feared that Ugandan President Idi Amin might be incensed at the Senate legislation in which Amin was accused of "genocide," and that Amin might use the 200 Americans as pawns, as he has before.

Eighteen months ago, when President Carter accused Amin of murder after the death of Ugandan Anglican Archbishop Janani Luwum, Amin forbade the 400 Americans then living in Uganda to leave the country and ordered them to Kampala, the capital, for a showdown meeting.

The diplomats said that Friday's 73-to-1 Senate vote, aimed chiefly at Ugandan coffee exports which supply Amin with 93 percent of his foreign exchange, might trigger a similar reaction from the mercurial dictator.

Amin, who in January declared 1978 a year of "love and reconciliation," has been denounced througout the world for the deaths of an estimated 250,000 Ugandans during his rule.

State Department sources, however, played down concern for the safety of the Americans in Uganda, who are mostly missionaries scattered over the East African nation's countryside.

The sources noted that Amin has previously differentiated between actions by the White House and those by Congress. Ugandan diplomats have been closely following the Senate's action, and are unlikely to read it as a slap from the Carter administration, the sources said.

The administration, which has been trying to deal with human rights violations in Uganda through international bodies such as the U.N. Human Rights Commission, has sought to avoid direct confrontation with Uganda, and did not support the Senate action.

The Senate vote will probably have little impact on Uganda anyway, sources say.

Earlier this year, the major American coffee companies, which has been purchasing a third of Uganda's coffee, voluntarily ceased buying it after the House passed a resolution urging them to do so. Uganda probably can find a market in Europe for the coffee it once sold to U.S. companies. Two thirds of Uganda coffee exports have already have been going to European countries.

Uganda's real problem, sources said, is not where to sell coffee but how much it can be sold for.

World coffee prices tripled between August 1976 and April 1977, but have sagged this year, partly because of an increased supply.

Coffee-producing nations earlier this year were forced to buy back beans on the world market to keep prices up.

The Ugandan economy, generally in chaos since Amin took power in 1971, is believed by observers to produce only 40 percent of the coffee tonnage it once was able to export.

With the high prices that have given coffee the nickname "black gold" in East Africa, Uganda was able to maintain its foreign exchange reserves despite the decreasing production.

Ugandan government receipts for coffee are also affected by smuggling. Like other East African nations, Uganda requires that farmers sell their coffee to the national coffee board exclusively.

But Ugandan growers, who are paid for their crops by the board in scrip redeemable for virtually worthless Ugandan shillings, often choose to smuggle the coffee to Kenya, where they sell it illegally for Kenyan currency.