Efforts to protest the interests of Americans still living in Uganda have placed West German diplomats in a new and delicate role which U.S. officials says has been handled very well thus far.

Normally, the Swiss government, and to a lesser extend the French, handle American affairs in countries in which the United States either has no embassy or no relations.

But since the United States pulled its last diplomat out of Kampala, the Ugandan capital, and closed its embassy there on Nov. 10, 1973, without actually breaking relations, the task of "protection of U.S. interests" has fallen to the West Germans, who have one of the few Western embassies still operating there.

It is basically a new role for the West Germans, though they also provide similar services in the Congo Republic for the United States. But it is one fraught with both personal and diplomatic danger because of the tense and unpredictable situation in Uganda today.

West German officials refuse to discuss their role at all in behalf of the roughtly 240 Americans, mostly missionaries, in Uganda. Other diplomats do so only guardedly.

One reason is that the term "protection of interests" which is standard diplomatic language for such assignments, is one that is not liked by Ugandan ruler Idi Amin, who considers himself the only one who can protect anybody's interests in his counrry.

Secondly, there is the unspoken fear among displomats that they are simply dealing with an irrational situation and thus they are not looking for any detailed publicity or suggestions that they are being especially active.

"The German role is not so much to contribute to a solution of the situation," one U.S. diplomat said, "it's just that they did everything right as a protective power. They made no mistakes."

The current U.S.-West German arrangement to handle U.S. affairs in Uganda is unique in other ways as well.

Normally, such arrangements are setup in Washington.

But the West Germans insisted that the hub of the new link with Uganda be in Bonn, the West German capital, rathern than Washington. For one thing, the West Germans wanted their Afridan experts handy. For another, communications are better.

The West German Foreign Ministry and the U.S. embassy here insist they are both no more than really insist they are both no more than really "post office boxes" for communications between Washington and Kampala.

But both have setup a round-the-clock "watch" on the situation. The West German embassy in Uganda has been very helpful, Western sources say, trying to keep track of the number of Americans still in that country, maintaining records on them, talking to them, and advising them to remain calm.

When President Carter sent thanks last week to Amin for Amin's assurance that the lives and safety of the Americans in Uganda were not endangered, the message was delivered orally by West German Ambassador Richard Ellerkmann.

After I learned that an American tourist in Uganda, Brian Schwartz, 24, of New York City, had been imprisoned on Feb. 26, the West Germans visited Schwartz in jail and he was released on March 1.