The Alexandria City Council early yesterday morning delayed until October a decision on whether to approve a controversial office complex planned along the George Washington Memorial Parkway south of National Airport.

The decision provoked cheers and applause from a group of about 50 local residents wearing decals that read "Stop-Think-Oppose-Prevent Parkway Project."

They objected to the increased traffic that the four buildings of the 200,000-square-foot complex would bring to an already-congested portion of the highway.

The council voted unanimously to grant a National Park Service request for 90 days to study the project's impact after more than 90 minutes of often emotional testimony from the residents as well as the attorney for the developer, Potomac Investment Associates of Potomac.

"Time is not of the essence here," condominium resident Michael Rauh told the council. "If you rush this project through, you do a disservice to the citizens. The only person who is in a hurry here is the developer."

The developer's site plan had received the necessary approval by the city's Planning Commission in May, but opponents and the National Park Service appealed the decision to the council. The council had deferred a decision until the developer and city planners could attempt to reach a compromise.

The proposal they reached included provisions for widening the parkway's nearby roads and moving the office buildings farther from the highway. But residents argued that widening the roads would do no good unless the Park Service is willing to widen the parkway median.

Under the terms of a 1929 agreement with the Interior Department, the city must have Park Service approval for any changes to the parkway. Park Service Associate Regional Director John G. Parsons told the council that he could not promise that approval until the agency has more time to study the proposal.