Members of Sen. Harrison A. Williams' personal staff testified today that the New Jersey Democrat took no official actions to benefit an Arab "sheik" or businesses in which he allegedly held a hidden interest.

Defense attorneys at the Abscam bribery trial of Williams and codefendant Alexander Feinberg are trying to diminish the impact of secret FBI videotapes that show the senator boasting of his influence and agreeing to seek government contracts for titanium after the fictitious sheik promised them a $100 million loan. Williams allegedly accepted stock he thought would be worth $12.6 million in the titanium mining venture.

Paul L. Skrabut, the senator's legislative director, whose legal fees are being paid by the senator's defense fund, testified that the senator was often required to tell foreign dignitaries what they wanted to hear while he was traveling overseas. Calling the practice a sort of "formalized hypocrisy," Skrabut said the senator would "have to say things no one takes too seriously, but are required because of the situation."

The aide recalled a 1978 visit to Saudi Arabia when the proposed sale of F15 jet fighters to the Saudis was a sensitive issue. He said the Saudi hosts were pleased by Williams' remarks at a reception and surprised when he later voted against the sale.

When presenting their case last week, government prosecutors played for the jury a videotape in which the senator pledged to help the sheik, actually an undercover FBI agent, to emigrate to the United States. Betty Ann Scott, who handles immigration matters in William's office, testified that the senator never mentioned anything about the sheik to her.

Anticipating a defense that the government entrapped the senator, prosecutors have introduced evidence that Williams held hidden interests in other businesses and thus was predisposed to accept a bribe. One witness, for example, said the senator agreed to help him get permits for a garbage recycling business in return for secret shares in the company.

Skrabut, however, noted that Williams had voted twice in 1976 against tax measures that would have aided garbage recycling firms.

Skrabut, an attorney, told a reporter after his testimony that he had questioned whether the senator should be paying legal fees for his staff's grand jury appearances, but decided it was the only practical approach. Williams asked the Senate Ethics Committee last year for permission to set up a legal defense fund. And the regulations governing the fund were published last fall.

In a legal matter not heard by the jury today, U.S. District Court Judge George C. Pratt rejected defense motions to dismiss the bribery counts in the indictment on grounds that the stock was worthless.