The National Capital Planning Commission, the federal monitor of Washington's growth patterns, put itself onto a collision course with the District of Columbia's municipal planners yesterday by voting to oppose the city's plans to restrict development along a four-block section of Connecticut Avenue above Dupont Circle.

By a vote of 7 to 3, NCPC members decided after three hours of debate that a proposed curtailed zoning plan adopted tentatively by the D.C. Zoning Commission would not assure the desired preservation of existing three- and four-story Victorian-era buildings in the neighborhood.

The Joint Committee on Landmarks, which is charged with preserving the city's historic structures, previously had adopted a position similar to what NCPC voted yesteerday.

The NCPC action is advisory, but influential, and such votes rarely are ignored by the city. The Zoning Commission will not act on the issue again until next month.

Existing zoning on the four-block section of Connecticut Avenue from Dupont Circle to the historic 19th Century city boundary at Florida Avenue permits buildings to rise to a 90-foot height. The 50-foot stopgap limit while permanent historic-area zoning was considered.

The Zoning Commission, in a decision that satisfied neither developers nor historic preservationists, voted 3 to 1 in January to adopt a permanent 70-foot, six-story building height limit and rules permitting buildings to occupy larger portions of their lots than now permitted. Under the city's 1975 Home Rule Act, the NCPC is required to advise the Zoning Commission on major actions prior to final adoption of zoning changes affecting the federal interest in the capital city.

NCPC members agreed yesterday that preservation of the 1971 L'Enfant plan for the capital, which includes Dupont Circle, is important to the federal interest.

In its first vote yesterday, NCPC members deadlocked 5 to 5 in rejecting a proposal to hold all buildings in the four-block stretch to a 50-foot height. a

The resolution opposing the Zoning Commission's more liberal action was approved later when NCPC members decided to urge the city panel to adopt an entirely new historic zoning category that would be "more compatible with the existing character of this portion of the [Dupont Circle] historic district that would more closely reflect the existing character and pattern of development."