Government prosecutors disclosed for the first time yesterday that John W. Hinckley Jr., accused of attempting to assassinate President Reagan, has claimed that he was not trying to shoot the president.

In papers filed in U.S. District Court, the prosecutors said Hinckley has claimed "that he was not trying to shoot the president, but rather trying to hit the president's limousine."

The government revealed the claim by Hinckley in an effort to persuade Judge Barrington Parker that videotapes of the shooting and testimony by victims should be allowed at Hinckley's trial.

The videotapes, made by television cameramen at the scene, are the "best evidence" of exactly how Hinckley aimed his weapon and fired the shots, the government said.

Hinckley has admitted that he shot Reagan, his press secretary, a D.C. police officer and a U.S. Secret Service agent. He contends, however, that he was insane at the time and should not be held criminally responsible for his actions.

Defense lawyers, in papers filed with the court earlier this week, argued that the videotapes and victims' testimony would be unfairly prejudicial to Hinckley, since he has already admitted firing the shots.

The prosecution, in the angrily worded response filed yesterday, said Hinckley was trying to have the jury "forget the crime altogether."

Limitation on the evidence about the crime would deprive the jury of the "critical information it must have" to evaluate the question of Hinckley's intent and his criminal responsibility, the government said.

Defense lawyers, who have maintained that the only issue at the trial would be Hinckley's sanity, declined to comment on the papers filed yesterday. Prosecutors refused to say when or where Hinckley claimed he was aiming at the car rather than Reagan.

Parker has scheduled a hearing in the case for Monday.