Gen. Robert Neller said that an investigation by the Naval Criminal Investigative Service, as well as the work of the task force, must proceed with caution.
"We don't want to be in a hurry," he told reporters at the Pentagon. "We want to make sure we're thorough and we're within the law ... This affects our entire organization."
The newly formed task force will monitor the progress of the criminal investigation and determine whether the victims received appropriate support, Neller said.
"They're going to look at what's going on, while developing plans for corrective actions and recommendations to policies, procedures, education and training of Marines that will prevent this in the future and the culture -- I'd say subculture -- that may have given rise to this," he said.
Neller said that fewer than 10 alleged victims had officially come forward and urged others to report abuse.
"I need their help," Neller said. "I'm going to ask them to trust us. I understand why that might be a bit of a reach for them right now. But I can't fix this... The only way there is going to be accountability in this is somebody comes forward and tells us what happened to them."
The commandant praised women in the Marine Corps.
"We've been fighting for 15 years, men and women side by side," he said. "And women, they did their thing. And I don't know what else they've got to do ... They just wanted to do their job. Let them do their job."
The scandal began with a news about lewd photos being posted by a group of Marines and former Marines on the Facebook group Marines United.
Photos of nude and clothed female service members have been posted to another image-sharing message board, Business Insider reported. A CNN review of the site found photos of women in uniforms from different branches of the military -- and nude and partially nude images.
Four branches of the military are looking into the posting of nude photos of what appear to be female service members on various websites, a Pentagon official told CNN on Thursday
Thomas Brennan, founder of the military news site, The War Horse, first reported the Marines United page to the Marines and NCIS.
After the NCIS announced its investigation, members were redirected to new pages where some taunted investigators.
One observer, Paula Broadwell, a former military intelligence army reservist, told CNN on Friday that Neller did not go far enough in addressing what she called a culture of sexual harassment and assault against women.
"I think a lot of women were watching and wanted to see what his response and what the tone of it was and he's clearly wrestling with how to combat this issue," she said. "But I still feel like he wasn't strong enough. That was still a kind of tepid response. He needs to come out in no uncertain terms and say this unacceptable, if you're doing this, we don't want you in the corps."
Defense Secretary James Mattis, in a statement Friday, said the actions of those behind the online postings represented "egregious violations of the fundamental values we uphold at the Department of Defense."
"Lack of respect for the dignity and humanity of fellow members of the Department of Defense is unacceptable and counter to unit cohesion," Mattis said. "We will not excuse or tolerate such behavior if we are to uphold our values and maintain our ability to defeat the enemy on the battlefield."