No reasonable person expects Israeli officials to kowtow to the United States just because of the billions of dollars in aid that American taxpayers have poured into their beleaguered country. But surely it's not unreasonable to ask that an American passport be treated with respect in Israel; our countries have, after all, been the closest of allies for the 39 years of Israel's existence as a state.

But the unpleasant, undeniable fact is that Israeli officials have been looking past some American passports and discriminating on the basis of race, color and creed. As longtime champions of Israel, we make this charge with sincere reluctance.

Citing the demands of national security, Israeli officials have regularly detained Americans of Arab extraction, those with Arabic surnames and black Americans. Some have had personal items confiscated arbitrarily or been humiliated by strip searches. Others have had their American passports held, and several have been required to post substantial bonds to ensure their good behavior while in Israel.

Last November we detailed the sorry treatment meted out by Israeli officials to Dr. Omar Kader, a distinguished American businessman. He was rudely interrogated for more than three hours at the Israeli-Jordanian border and had personal property confiscated on ludicrous grounds.

After our report was published, an Israeli Embassy official in Washington said he ''strongly disagreed'' with and ''resented'' our suggestion that Arab-Americans were being treated any differently from other Americans by Israeli border officials. We were unimpressed by his claimed indignation, and the mail we received in response to that column -- as well as subsequent events in Israel -- clearly showed that the embassy spokesman's denial of discrimination was ridiculous.

A grocer in Westley, Calif., wrote: ''As an Arab {Palestinian} American who has flown back many times to visit family, I know the humiliation and degradation that Mr. Kader must have gone through.''

Judith E. Tucker, an assistant professor of history at Georgetown University, called Kader's ordeal ''an experience similar to my own.'' Because she is married to an Arab-American, she and her 1-year-old daughter were singled out in the summer of 1985 ''to receive honorary Arab treatment,'' she wrote. This is her description of that treatment by Israeli border officials:

''We were thoroughly strip searched (including the diaper) and every item we were carrying was prodded, X-rayed and/or photocopied. The stroller was taken for 'examination' and returned to us damaged beyond use or repair -- we had to abandon it.

''Faced with the prospect of a summer without a stroller and with a pre-ambulatory baby, I complained loudly and bitterly to the Israeli official in charge. He eventually had me fill out a formal complaint form and assured me that compensation ($85 for the stroller) would be coming my way within a few weeks. That was over 16 months ago and . . . I have yet to receive any compensation, much less an apology."

The State Department has lodged several protests with the Israeli government complaining about the mistreatment of Americans.

So far this summer, at least 75 incidents have been reported to Foggy Bottom. Forty involved Arab-Americans and 35 involved black Americans. The blacks were apparently picked on because Israeli officials feared that they were connected with an American sect known as Black Hebrews. Some 1,500 of the sect's members have settled in Israel, despite official efforts to make them unwelcome.

Besides their concern with security, Israeli officials have excused their actions as a means of preventing Arab-Americans and blacks from settling in their country. As part of this policy, Israeli officials have retained the passports of some Americans to ensure that their stay is a short one. Another method is to require the posting of a large bond -- as high as $5,000 -- which is returned only when the targets of suspicion leave Israel.

The State Department has informed Israel that if the harassment and discrimination directed at certain Americans are not stopped by the middle of August, a formal ''travel advisory'' will be issued to all Americans planning to visit Israel.

These advisories are usually issued only because of unstable political conditions, random violence, anti-American terrorism or specific health problems in the cited country. Even though the proposed advisory on Israel would merely warn blacks and Arab-Americans of possible harassment, it would be a stunning insult to Israel.