SAN JUAN — Mayor de Blasio weighed in on the Quentin Tarantino controversy for the first time on Thursday — criticizing the film director for making a “very insensitive comment” about cops right after an NYPD officer was killed in the line of duty.

Asked in Puerto Rico if Tarantino should apologize for equating cops with “murderers” at a police reform rally in New York City last week, the mayor instead urged the director to “come forward” with a more positive message.

“I think it was a very insensitive comment, both in the way he said it — it’s just not the right phrase to use about law enforcement officers – and that he said it just days after the death of Officer Holder.”

NYPD officer Randolph Holder was gunned down by a 30-year-old gang member on Oct. 20 after he responded to a wild shoot-out in East Harlem.

“I can’t believe if he wants to see improvement in the relationship between police and communities, if he wants to see reform – that’s not the right language to use,” Hizzoner added of Tarantino. “And he should come forward and say that.”

Tarantino’s remarks caused a fury among police officials – including NYPD commissioner Bill Bratton – and sparked calls for a boycott of his next film from police departments around the country.

Tarantino has since said his criticism was directed at a small minority of officers but he has refused to cave in to demands that he apologize.

De Blasio was unrelatedly asked about concerns that the police union could engage in a work slowdown in response to proposed raises its members deem unsatisfactory.

“We have no indication of that,” said the mayor, who was in Puerto Rico to march against the federal government’s inaction regarding the island’s dire financial picture.