Police Commissioner James O'Neill says he won't march in this year's Puerto Rican Day Parade.
The commissioner says he may attend to help officers working the route, but he won't take part in the festivities because of the plans to honor Oscar Lopez Rivera.
The Puerto Rican nationalist became a free man last week after nearly four decades in custody for his ties to an extremist group.
It was responsible for more than 100 bombings across the country, including one in Manhattan, but Lopez Rivera was never linked to any specific attack.
"I cannot support a man who is a co-founder of an organization that engaged in over 120 bombings, six people killed and seriously injured, four police officers," O'Neill said.
Parade organizers are sticking by their decision to have him take part, and several city officials were joined by members of the service workers Union to support Lopez Rivera.
"Many in the Puerto Rican community, here and on the island, are elated to have him here as he represents the tenacity, the conviction and resolve of what it is to be Puerto Rican," said City Council Speaker Melissa Mark-Viverito.
Other police organizations have also decided not to participate on June 11, including the NYPD Hispanic Society and the Lieutenants Benevolent Association.