With this Christmas campaign, many felt Balenciaga went too far: children were photographed posing with teddy bears wearing fetish leather harnesses used in sadomasochistic bondage practices.
Additional photos from the campaign showed filings from the US Supreme Court on child abuse.
On social media, many users expressed irritation or shock.
Reality TV star Kim Kardashian, who works with the brand, announced that she is reconsidering her relationship with Balenciaga.
The company has already asked for forgiveness for the staging, and now chief designer Demna Gvasalia has also spoken out.
In a post on Instagram on Saturday, he wrote: "I would like to personally apologize for the wrong choice of concept for the gifts campaign with the children and take responsibility for it.
It was inappropriate to have children promote objects that have nothing to do with them.
As much as I sometimes want my work to be thought-provoking, I would NEVER intend to do so with a subject as horrific as child abuse, which I condemn.”
He wants to learn from the mistake by getting in touch with child protection organizations and learning how he can "help work against this terrible issue".
He apologized to anyone who "feels offended by the portrayal" and noted that Balenciaga has pledged to take "reasonable steps" to protect children's welfare in the future.
The company had already issued a letter of apology.
It said: "We take this matter very seriously and are taking legal action against the parties responsible for the creation of the set and use of unauthorized items for our Spring 23 campaign photo shoot.
We condemn in the strongest terms child abuse in any form.
We are committed to the safety and well-being of children.”
Balenciaga is a billion-dollar brand owned by Kering, the world's second largest luxury group.
As chief designer, Demna Gvasalia is in control of the creative process.