President Reagan yesterday personally assured Federal Reserve Chairman Paul A. Volcker that he has not decided whether to replace him when Volcker's term as chairman expires in August, White House officials said.

Aides earlier this week were reported as having decided that Volcker should not be reappointed and that the president should replace him "with his own man."

But at the end of a meeting yesterday of Reagan's Economic Policy Advisory Board, which Volcker usually attends, the president turned to the Fed chairman and said "I'm sorry about this spate of stories. I want you to know that I have simply not addressed this issue yet."

The two men then shook hands "and there were a lot of smiles," an administration official present said. "The president wants to put this little fire out," the official said. "He wanted to reassure Volcker himself."

However, Reagan's comments do not change the reality that most of his senior advisers other than Martin Feldstein, chairman of the Council of Economic Advisers, apparently favor a change at the Federal Reserve.

Sources who have talked with them say the reasons vary, with some focusing on the political gains that might be made if Volcker and the Fed can be blamed for high interest rates and the recession, while Reagan takes credit for the recovery now under way and the drop in inflation.

The administration generally endorsed the Fed's tight money policies that contributed both to the recession and to the improvement in inflation, although Reagan and other officials at times criticized specific implementation of that policy by the central bank.

The advisers opposing Volcker's reappointment reportedly favor naming either Fed Vice Chairman Preston Martin, a Reagan appointee, or former CEA chairman Alan Greenspan to the post. Greenspan has praised Volcker's actions as chairman and recommended his reappointment.

White House spokesman Larry Speakes said that there has been "no organized, authorized personnel search" for a Fed chairman. "The personnel group has never met on the subject."