Harvard will attempt to block a measure that would change dramatically the zoning controls in Harvard Square, a University official said last week.

If the Cambridge Planning Board approves the measure, sponsored by the Coalition for Harvard Square, three consecutive Council majorities would be needed to make it law.

A major zoning plan ordinarily needs a 6-3 majority on the Council to pass, but a landowner of 20 percent or more of the area may object to the plan and require that it receive seven votes to pass. Harvard owns more than 20 percent of the land in the Square and will exercise its right to demand a 7-2 vote for passage, said Associate Vice President for State and Community Affairs Jacqueline O'Neill.

The Coalition for Harvard Square, formed in November 1987 to begin the Campaign to Save Harvard Square, includes Harvard Square Defense Fund activists, residents from the Square and bordering neighborhoods, Harvard affiliates and local merchants and attorneys.

Members of the Coalition said their effort to limit development has particular immediacy now because of what they call a surge of real estate proposals made in the last year, most of them around the southwest part of the Square. The Coalition guidelines identified several projects as too dense or too high, including the replacement to the Club Casablanca building, a commercial-office complex slated to replace the Harvard Motor Inn, and the building to replace the Blue Parrot bar.

O'Neill said there is no need for new zoning regulations.

But Donham Professor of Organizational Behavior Paul R. Lawrence, a city-appointed adviser on Square development, said, "The petition offers the only politically feasible way to increase affordable housing and decrease the overdevelopment of the Square."

City Councillor Alice K. Wolf said she was "not surprised that Harvard, an active developer, would decide" to try to prevent the zoning changes.

And Gladys P. Gifford, a Coalition member, called Harvard's decision a "tragic response for the neighborhood, and one that would spoil its own nest."

Three May Vote Against

Two Councillors, Walter J. Sullivan, Jr. and William H. Walsh, said they would definitely oppose the petition, and a third, Thomas Danehy, said his "instincts are against it" but that he wants more information. If Danehy opposes the plan he will provide a third negative vote, making a victory for the Coalition unlikely.

Walsh said the plan "looks good and sounds good, but we really need a city-wide comprehensive zoning package." And Walter Sullivan said, "I agree with Harvard. I am always against downzoning."

But Wolf criticized Harvard's intentions to attempt blocking the zoning controls. "Harvard's responsibility as a public body, which is vast because of all its tax-free land, conflicts with its role as a real estate developer," she said.

Tactic Last Used on Linkage

The last time Harvard exercised its right to require a seven-vote majority was in 1984, when it teamed with MIT to block a linkage proposal aimed at forcing developers to build more affordable housing in Cambridge.

Gifford, who is also a member of the Harvard Square Advisory Committee, said Harvard should get out of the real estate business, adding that the University breaks community ground rules as it searches for zoning loopholes.

But Harvard's O'Neill defended University real estate policies in the Square.

"Harvard has to grow and build to support its teaching and research," she said. "What they build, which, importantly, is non-profit, parallels its abilities to directly support the University staff and students, to be competitive."

O'Neill said she does not see the Coalition as an adversary. Although Harvard opposes the proposed zoning changes, O'Neill called the issue a matter for "open public policy debate."

"Harvard has much more in common with its neighbors than not," O'Neill said, adding the University "will be looking at what we build long past when most of us are gone."