Former Police Commissioner Ray Kelly says the Sept. 11 attacks led to a total change at the NYPD and forced the agency to focus on counterterrorism operations.

But Kelly, who served as police commissioner from 2002 through 2013 under former Mayor Michael Bloomberg, is pushing back against criticism that the department went too far with its surveillance tactics.

"Everything that we did was constitutionally appropriate," Kelly said Saturday during an interview with NY1. "We made certain that that was the case with a whole cadre of first class lawyers that we brought on board."

"I think these are activists that make these accusations," Kelly went on to say. "I think the average person is not particularly concerned. If you go into a department store, you have your picture taken many, many times. This is the world in which we live. You can't push back on the technology. It's there, we have it, it should be used to make us safer. So I just don't buy those complaints. This being New York, you're always going to have a cadre of advocates who punch above their weight. All they have to do is complain and they'll get an article in the newspapers or get on television."

The agency came under particularly strong fire when a series of articles in the Associated Press revealed that the NYPD was monitoring Muslim communities across the five boroughs. The revelations led to lawsuits that were ultimately settled, with the city agreeing to pay damages and change its training policies.