After promising a “bigger vision” for creating more diverse schools, Mayor Bill de Blasio on Thursday seemed to temper expectations for the city’s soon-to-be-released plan to tackle segregation.

Responding to questions from reporters at a press conference, the mayor suggested the proposal is not so much a sweeping citywide plan as one that would improve diversity at “a number of schools.”

“I’m not in the business of lying to people. We’re not going to put forward a plan that says we’re going to instantly wipe away 400 years of American history and suddenly create a perfect model of diversity,” he said. “But we can make a major difference in a number of schools with some smart methodologies to increase the level of diversity.”

The mayor pointed to a recent, highly contentious zoning change in a handful of schools in District 3 as a “great example” of how the city can encourage integration. Community Education Council members in District 3, which includes the Upper West Side and part of Harlem, voted to shift attendance boundaries around a sought-after school where most students are white and an under-enrolled school where most students are black and Hispanic.

“They were very devoted to figuring out a way to have more diverse schools, but also high-quality schools for everyone,” de Blasio said. “We’re going to be looking to do more things like that.”

The rezoning began as an effort to relieve overcrowding, not an explicit attempt at integration. It’s too early to tell whether the zoning change will actually integrate schools, but many are skeptical it will have a major impact.

In August, the mayor said a “bigger vision” plan was in the works to promote integration in New York City schools, home to one of the most segregated school systems in the country. The administration has said the proposal will be released by the end of the school year in June, but the details have largely been kept secret.

Advocates for school integration recently called on the Department of Education to start a public engagement process to discuss the proposal, incorporate feedback and build support for whatever measures are ultimately implemented.

De Blasio and schools Chancellor Carmen Fariña have both faced increasing pressure to act decisively on school diversity. On Thursday, the mayor repeated his stance that schools are segregated because of their neighborhoods.

“Could we create the perfect model for diversified schools across the school system? No,” de Blasio said. “Because you have whole districts in this city that are overwhelmingly of one demographic background. You would have to do a massive transfer of students and families in order to achieve it. It’s just not real.”