Multimillionaire philanthropist and art lover Gregory C. Carr has learned one of the cardinal rules of Cambridge politics the hard way.

After drawing up blueprints to a new 320-seat theater in Harvard Square, Carr has recently run into opposition from residents, who have serious objections to a major new building project.

The Market Theater, designed to replace the old theater by the same name that Carr closed in May, was to be a four-story performing arts complex—a theater, a café and low-cost office space for non-profits—spanning at least 40,000 square feet of floor space at the intersection of Mass. Ave. and Arrow Street.

But now, in the face of community concerns, Carr has revised his plans. The Market’s redesign will include a substantially smaller theater, with only about 150 seats.

Early this fall, the theater seemed all but ready to be built. The Harvard Square Advisory Committee, a body that makes initial recommendations to zoning and planning committees, issued a report in which it “strongly endorsed” his plans. The Harvard Square Defense Fund gave its support to the project, and the Cambridge Historical Commission granted the plan a “certificate of appropriateness.”

But at a Board of Zoning Appeal meeting last month, Cambridge residents turned out in droves to express various objections to Carr’s proposed blueprints.

As a result of these concerns—about signage, the building’s restaurant, traffic flow and, in particular, a dearth of parking—Carr now says he has had to rethink some of his project.

“We are...considering a plan whereby the theater will have fewer seats,” Carr wrote in an e-mail. “This indirectly addresses, and eases, the parking issue.”

The revised plan would result in a theater not appreciably larger than the old 100-seat Market above Grendel’s Den, which Carr sold in part to gain a larger space.

While Carr said the revised plans will not lessen the quality of his work—“because we produce edgy and experimental theater and it works well in a smaller auditorium”—others are more concerned.

The American Repertory Theater (ART), currently housed in Harvard’s Loeb Drama Center, has recently been seeking a new space to replace the supplemental stage it lost when Harvard purchased the Hasty Pudding building for student use.

The ART had been considering using the new Market as this additional space, according to ART Executive Director Robert Orchard—though no final plan had been sealed.

Orchard said the smaller theater now in the works would not meet the professional acting company’s needs.

“The smaller space would not be a space that would have enough capacity to work for the ART as a second space,” Orchard said.

At the Board of Zoning Appeal’s meeting, whose purpose was to discuss requests for unusual signage and permission to have a retail restaurant on the site, numerous residents turned out to voice their views.