Sen. John Glenn (D-Ohio) sought today to reassure supporters of Israel that he "will never waver" in his backing of the Jewish state.

In a luncheon speech to the National Jewish Community Relations Council, Glenn tried to lay to rest suggestions "that my commitment to Israel is somehow suspect" or that he is "no friend" of Israel.

Glenn canceled a scheduled trip to Germany in order to use this forum to confront a political problem that his aides readily acknowledged as a threat to his undeclared candidacy for the 1984 Democratic presidential nomination.

Recent newspaper and magazine articles publicizing statements he has made, urging that the Palestine Liberation Organization (PLO) be brought into the Mideast negotiations, have been given wide circulation in the Jewish community by fund-raisers for other Democratic hopefuls, Glenn's press secretary, Greg Schneiders, said.

Today Glenn said, "I regret that past statements I have made on this subject have caused misunderstanding," and vowed to oppose exclusive negotiations between the United States and the PLO.

He also defended his vote for sale of advanced F15 fighters to Saudi Arabia in the Carter adminstration and his criticism of Israel's bombing of the Iraqi nuclear reactor.

"I don't deny that on occasion, I have made statements or taken positions that may be unpopular with some of you," Glenn told the 400 Jewish community leaders from around the nation. "I also know that we may not always agree in the future. But those who question my commitment to Israel are being neither fair with me nor honest with you."

The Glenn campaign's concern about the reaction of the politically potent Jewish community was triggered by an article in the Jan. 31 issue of New York magazine, in which reporter Michael Kramer asserted that Glenn has a "significant Jewish problem."

On Feb. 3 New York Times columnist William Safire wrote that "Many American supporters of a strong Israel do not consider him in their ranks.

Kramer cited statements by Glenn in 1979 and 1981 supporting negotiations with the PLO. American government policy has rejected such negotiations until the PLO recognizes Israel's existence and renounces terrorism.

In 1979, Glenn said, "The only way to get a final resolution of the Mideast situation is to get all the parties together, and that includes the PLO."

Glenn did not dispute the accuracy of that quotation or a similar statement two years later also quoted by Kramer. But he said today that he had always opposed "unilateral U.S. negotiations with the PLO . . . and until the PLO stops its terrorist activities and formally recognizes Israel's existence, there is no reason to expect Jerusalem to negotiate with them, either."

"We should not try to dictate that decision," he said. "The PLO has recently shown that it is capable of moderate words. Let it now prove that it is also capable of moderate actions."

As for the raid on the Baghdad reactor, Glenn said he shared "your concern about the danger an 'Islamic bomb' would pose to Israel's existence," but "I don't accept the proposition that military force was the only way to solve the problem."

He said he supported the sale of F15s to Saudi Arabia because there were "very important strings attached" limiting their use, and the alternative was the purchase of advanced French fighters "with no strings attached."

The audience applauded mildly when Glenn recalled that he had opposed the sale of airborne warning and control system (AWACS) aircraft and equipment to Saudi Arabia. It also applauded at four or five other points, but listened silently as he called for a moratorium on Israeli settlements on the West Bank and warned that Israel could not absorb the West Bank Arab population without changing its character.