President Reagan and President-elect George Bush were subpoenaed Friday by lawyers for former White House aide Oliver L. North to testify as defense witnesses at his trial on criminal charges stemming from the Iran-Contra affair.

Justice Department and White House officials said they will fight the subpoenas, which the White House said raise "significant legal and constitutional questions.""There's no question in my mind that there will be resistance to them (subpoenas)," said one senior Justice Department official. "There is a fairly extensive body of law that indicates that sitting presidents are not available for personal testimony in a courtroom."

No sitting president has ever testified in court in a criminal trial. Justice Department officials said Reagan's legal situation may be weaker because he will be a former president by the time of the scheduled start of North's trial Jan. 31.

"Bush would have a stronger claim to avoid testifying personally but an ex-president's claim would be strong also but for different reasons," possibly executive privilege and national security, one official said.

A White House official said that Reagan, who had been informed in advance of the subpoena, viewed the effort as an attempt to prod him into pardoning North before he leaves office. The official, speaking under conditions of anonymity, said that Reagan's view that the legal process should run its course has not changed.

North, charged with conspiracy to defraud the government, theft and several other felonies for his role in the Iran-Contra affair, is scheduled to stand trial 11 days after Reagan leaves office and Bush succeeds him. But significant pretrial legal hurdles involving the use of classified government documents remain to be cleared and could delay the start of the trial.

Sources said that officials from the State Department and the National Security Agency have also received subpoenas from North's attorneys.

Robert S. Ross Jr., executive assistant to Attorney General Dick Thornburgh, said North's lawyers contacted White House Counsel Arthur B. Culvahouse this week to inform him that they planned to subpoena Reagan and Bush. "It was agreed that the attorney general was the proper official in government" to receive the subpoenas, Ross said.

Ross said Thornburgh designated him to accept the subpoenas, which were delivered to the department about 2:15 p.m. Friday.

A cover letter delivered along with the subpoenas indicated that additional subpoenas seeking documents from Reagan and Bush will be issued soon, Ross said.

A White House spokesman said that Reagan, who was in Los Angeles, had been briefed Wednesday on the prospective subpoena in a telephone call placed from Washington by Culvahouse and White House chief of staff Kenneth M. Duberstein. Since then, Duberstein has joined the Reagan party in Palm Springs where the president and first lady Nancy Reagan are guests of publishing magnate Walter Annenberg.

Duberstein briefed Reagan Friday morning and informed him that the subpoena would be issued in Washington Friday afternoon.

"The receipt of this subpoena is not an unanticipated development," a White House statement said.

In the statement, the White House said, "Historical precedent suggests any relevant information could be provided through written questions and answers."

Reagan and Bush are not on the witness list submitted by independent counsel Lawrence E. Walsh, North's prosecutor. Reagan has responded to written questions from Walsh's office and Bush was interviewed by Walsh's staff.

The main conspiracy charge accuses North of corrupting the secret U.S. arms sales to Iran that Reagan had authorized in January 1986. The indictment says that North's use of profits from the Iranian arms sales to support the Nicaraguan Contras was unauthorized.

Reagan's testimony could be important to North's defense, which is expected to center on North's contention that he acted with the approval of his superiors.

Reagan and Bush have separately said they were unaware of the funds diversion to the Contras, which occurred at a time that Congress had banned military aid to the Contras. No evidence has emerged that challenges their statements.

North told the congressional Iran-Contra panels that he informed his boss, then-national security adviser John M. Poindexter, of the diversion. Poindexter testified that he did not pass the information to Reagan.