For the second time in two months, the U.S. government agency charged with monitoring development in the nation's capital officially declared yesterday that an action by the D.C. Zoning Commission would have a harmful effect on federal interests in the city.

By a 6-to-4 vote, the National Capital Planning Commission (NCPC) objected to George Washington University's proposal to erect a massive glass-fronted, 11-story commercial office building behind Red Lion Row, a group of 19th Century town houses on the south side of the 2000 block of I Street NW. The row faces two triangular parks that were first proposed in 1791 by Washington's original planner, Pierre L'Enfant.

The Zoning Commission, a municipal body, voted preliminary approval of the project last month but was required to seek NCPC advice before taking final action next Thursday. Related renovations to Red Lion Row must be reviewed by the city's Joint Committee on Landmarks.

In the other similar action, NCPC previously had contended that the Zoning Commission's tentative decision in February to reduce the current 90-foot building height limit to 70 feet on a four-block section of Connecticut Avenue above Dupont Circle would harm federal efforts to preserve Washington landmarks. NCPC supported a 50-foot height limit. That issue also is scheduled for final Zoning Commission action next week