WASHINGTON, April 2— An American lawyer who has been linked to the Jonathan Jay Pollard spy case said today that he had been a legal adviser to the Israeli Defense Ministry and that Israel had refused to allow him to be questioned in the United States.
The lawyer, Harold Katz, said Israel required that any interviews take place in Israel because of Mr. Katz's knowledge of ''sensitive'' matters at the Defense Ministry. The United States refused, he said.
Mr. Katz's acknowledgment that he worked for the Defense Ministry is significant because a little-known scientific unit of the ministry is believed to have run the espionage operation.
Reagan Administration officials said they believe that Mr. Katz, a citizen of both the United States and Israel who now lives in Israel, has detailed knowledge about the spy ring and could implicate senior Israeli officials in the Pollard investigation. Katz Denies Reports
In a statement released in Israel, where he is now in private practice, Mr. Katz denied reports that he assisted in payments to Mr. Pollard, who received more than $45,000 from Israel for his espionage activities.
''I did not take part in the Pollard operation,'' he said. ''I passed no monies to the Pollards or anyone on their behalf. I neither received nor handled any documents.''
According to Administration officials, Mr. Katz owned an apartment in Washington that was used by the spy ring to photocopy secret documents collected by Mr. Pollard from the United States Navy.
Mr. Katz acknowledged that he had owned a Washington apartment ''in connection with the Pollard operation.'' But he said that any use of the apartment for espionage purposes ''was without my permission or knowledge.'' A Rogue Operation
Mr. Pollard pleaded guilty to spying charges in the diplomatically sensitive case and was sentenced last month to life in prison. His wife, Anne Henderson Pollard, pleaded guilty to lesser counts and received a five-year prison term.
Israel has repeatedly referred to the spy ring as a ''rogue operation'' that was not approved at senior levels of the Israeli Government. But Administration officials said they believed that Mr. Katz might provide information disproving Israel's claim.
According to Mr. Katz's statement, the Israeli Government ''did not refuse permission to the United States prosecutors to question me.''
''Since I had dealt, within my duties as an adviser to the Ministry of Defense, with matters sensitive to the government of Israel, the government required that such interrogation take place in Israel, at the United States Embassy if need be,'' he said. ''The prosecutor declined.''
Mr. Katz's laywer, Richard A. Green of Washington, said that Mr. Katz had ''no knowledge of the Pollard matter'' and was not facing criminal charges. ''We've been told by the United States Attorney's office that he is not a target of the investigation,'' Mr. Green said. Two Apartments Were Involved
Three other Israeli officials and a former secretary in the Israeli Embassy here, Irit Erb, have been named as co-conspirators in the Pollard case.
According to Administration officials, Ms. Erb's and Mr. Katz's apartments were in the same Washington building. The Justice Department has said Mr. Pollard delivered secret documents to Ms. Erb's apartment.
Yossi Gal, a spokesman for the Israeli Embassy, said the Israeli Government had no comment on the case.
