“I didn’t want one case to dominate the movie,” French child actress turned writer-director Maiwenn, 36, says of the many vignettes that make up her third feature, “Polisse,” a fast-paced study of the day-to-day lives of police officers in a Paris child protection unit as they go from eating cereal with their kids to interrogating suspected pedophiles. The dialogue (co-written with her friend Emmanuelle Bercot, who also stars as one of the officers) is as blunt and unadorned as the fluorescently lighted rooms where much of the action takes place, giving it a hardboiled documentary feel. Maiwenn also has a starring role as Melissa, a photographer documenting the unit at work. The movie, in French with English subtitles, won the Jury Prize at Cannes last year.

“I wasn’t trying to go for a TV or documentary style, but I wanted something that was real,” she says, curled up in a loose-fitting gray sweater and skinny jeans on a couch in a retro-styled boutique hotel. “I do not at all have the vocation of a documentary filmmaker,” she stresses, although the initial idea for the project came to her from watching a TV documentary on the child protection unit. It prompted her to contact the unit through the station and led to her observing them working on cases. She declines to say for how long.

“I was watching them all day long and taking notes. Then I started writing. I worked six months all by myself, and I had a huge script. Then I asked her (Bercot) to help me out for structure,” Maiwenn (who dropped her last name, Le Besco, when she was a teenager) says in near monotone. She speaks mostly through a translator, although her English is good.

“Everything is interconnected. It’s a whole. I didn’t decide to become a film director. I just wanted to see this movie,” she says in English, with a hint of passion. It’s apparent from the film that she has a lot to say, but extracting her thoughts can feel like stepping into an interrogation room.

She’ll say something loaded, such as, “It’s difficult to have all the actors together. They have lots of ego and big personalities.” When asked what specifically came up in regard to ego during the shoot, she bursts out laughing. “I cannot be deeper in my answer.” There’s a pause and then she says something unrelated, praising a young actor who delivers a moving performance in a pivotal scene in which a Muslim woman asks the unit to take care of her son because she can no longer provide for him.

“We did it in one take, and that’s the incredible performance that I got,” she says, adding that she bribed the child with a remote-control helicopter he had his eye on.

Some of the film’s most striking scenes involve young children, and it’s clear by their performances she works well with them. She has two of her own, although she says she doesn’t think her role as a mother influenced how she made the film. She shies away from talking about her children, even as her oldest, Shanna, 19, stands a few feet away from us, taking pictures. Maiwenn met Shanna’s father, director Luc Besson, when she was 12 and then dated him as a teenager.

She’s able to tap into the conflicting feelings of children and provide them with the comfort to deliver powerful performances, especially in uncomfortable scenes. “He loves me too much,” a young girl reluctantly confesses to her mom one morning while getting ready for school in a particularly chilling scene. The mom asks what she means, and the girl simply repeats it. It couldn’t be a less sensationalistic moment. Maiwenn’s never seen “Law and Order: SVU,” and yet “Polisse” often feels like a refutation of its formulaic plot lines and overblown emotions.

“I had no lead characters in my initial writing of the script,” she says.

The relationship between her character, Melissa, and a member of the unit, Fred (played by French rapper-turned-actor Joeystarr) stood out to her. “I wanted to show a culture shock between two human beings. You have this bourgie, drawn-in sort of conventional character. Then you have Joeystarr in opposition.” Fred’s passion becomes a liability as he grows increasingly unhinged by the bureaucratic entanglements the unit comes up against, but his connection with Melissa has the potential to ground him. “Being at the precinct, they develop a relationship that brings my character back to her origins and herself really. There was a cultural opposite that ended up not really being an opposite.”

It’s in this gap of contradictions that Maiwenn thrives. Labels only go so far to describe her characters. They often surprise and confound. Her writing with Bercot bears these complexities even if she’s unable or unwilling to express them.

“You cannot ask me how it is to make a movie,” she says exasperatingly and then adds more softly, “this was the most difficult film I’ve made.”

Polisse opens May 25 at Landmark E Street Cinema.