Garfinckel, Brooks Brothers, Miller & Rhoads Inc. reshuffled its top management yesterday, promoting its two executive vice president to new jobs as president and vice chairman of the Washington retail conglomerate.

Named president was Manuel B. Rosenberg, 49 who had been executive vice president-merchandising.

Promoted to vice chairman was Robert Vandemark, 58, who previously was executive vice president operations and finance.

David R. Waters, who has been both chairman of the board and president, became chairman and chief executive officer under the new line up.

Also promoted was Frank T. Reilly, president of Garfinckel's Brooks Brother's division and until now a corporate vice president, who becomes senior vice president.

As president, Rosenberg will take responsibility for four Garfinckel retail operations -- The Miller & Rhoads and Miller's department stores and the Ann Taylor and Harzfeld's specialty shops. A former chairman and chief executive of Gimbel's Philadelphia division, Rosenberg moved to Garfinckel Corp. in 1977.

Vandemark will continue to be the main money man in the Garfinckel executive suite with specific responsibility for raising capital for expansion and new acquisitions, the announcement said.

Under the new table of organization, the presidents of the four chains under Rosenberg will report to him. Reiley and the chief executives of the Garfinckel stores and the Catherine's Stoute Shops division will report to Waters.

Besides reducing the number of executives reporting directly to Waters, the reorganization will "focus the talents of senior management in those areas of greatest challenge and opportunity for the corporation in the 1980s," Walters said in a statement.