Parents with children in charter schools railed against Mayor Bill de Blasio Thursday at a City Hall protest organized by the pro-charter group Families for Excellent Schools.

“Mr. Mayor, apologize for insulting charter school children,” said Sharita Moore-Willis, whose daughter is a first-grader at Girls Prep Lower East Side Charter Elementary School. “Start acting like a mayor for all kids.”

She and other parents were incensed by the mayor’s comments at a press conference Wednesday where he attributed some charter schools’ higher state test scores to test prep rather than learning. “If that’s where they put a lot of their time and energy, of course it could yield better test scores. But we don’t think that’s good educational policy,” he said. “So we have a different approach, but we think that approach is yielding better results in terms of actually teaching kids.”

Joe Herrera, whose two sons attend Coney Island Prep Charter, disputes that claim. He said one of his sons jumped a year and a half in reading after just three months at the school. “Parents want what is very best for their kids,” he said.“That’s not the case with some special interest groups or elected officials. It’s a political agenda, not an education agenda.”

On Thursday morning, the mayor addressed the issue again in an interview with WNYC’s Brian Lehrer, this time suggesting that some charter schools have higher test scores because they exclude lower-performing children, a clear dig at Success Academy. “We do not believe in a test-prep heavy model, we do not believe in excluding students with special needs and who are English Language Learners. We do not believe in excluding kids with behavior issues that have to be addressed or who don’t test well,” he said.

But he also tried to distinguish between different types of charter schools. “Some charters, sadly, have a long history of exclusion. Others are very inclusive. In fact, more inclusive than the dynamics within their district. I commend those, I applaud those, and we work well with those.”

At a visit to Harlem’s DREAM Charter School in June, the mayor told Politico that his perceived antipathy toward charter schools was overblown. “It’s not shocking that in politics things get distilled down to a sentence or a phrase, and once it became seemingly a conflict between me and one of the heads of the charter organizations, that became the dominant story,” he said. “Rather than the much richer and real story of working together.”

But pro-charter groups, in a notable display of unity, say his recent comments are evidence he’s biased against their schools.

“We get by now that the mayor doesn’t like charter schools and that he seems constitutionally incapable of hiding it,” said James Merriman, CEO of the New York City Charter School Center, in a statement. “But it is ungraceful and mean-spirited to show his contempt by belittling the record number of students of color who worked so hard to master the common core standards as this year’s state test results reflect.”