SIOUX CITY, IOWA - JANUARY 05: Sen. Elizabeth Warren (D-MA) speaks to guests during an organizing event at the Orpheum Theater on January 5, 2019 in Sioux City, Iowa. Warren announced on December 31 that she was forming an exploratory committee for the 2020 presidential race.  (Photo by Scott Olson/Getty Images)
CNN  — 

Sen. Elizabeth Warren said Monday that she had apologized to Cherokee leaders for sparking “confusion” by her use of a DNA test to prove Native American ancestry, adding that she didn’t mean to cause any “harm” to the tribe by citing her heritage “decades ago.”

“I’m not a tribal citizen and I respect the difference,” the Massachusetts Democrat told CNN in the Capitol on Monday. “Tribes and only tribes determine tribal citizenship.”

Warren, who is expected to announce her presidential run this weekend, said she’d had a “good conversation” with the Cherokees’ Principal Chief Bill John Baker last week.

“I told him I’m sorry for adding confusion about tribal citizenship and tribal sovereignty and for harm caused to native tribes – and also for not being more mindful of that decades ago,” Warren said.

Last fall in a carefully choreographed video, Warren announced the results of a DNA test that showed ties in her ancestry to Cherokees – in an attempt to push back at the derisive attacks waged by President Donald Trump, who lampoons her as “Pocahontas.”

The DNA results claimed “strong evidence” of Native American ancestry “6-10 generations ago.” But it only served to intensify the criticism given her distant ties.

The issue first came to light in Warren’s 2012 Senate race, when it was revealed that her Native American ties were touted in the early part of her teaching career, raising the specter that she had used her status to help advance professionally. But the Boston Globe, in a lengthy investigation last fall, reported that her Native American ancestry had not been a factor in her rise through academia.

Julie Hubbard, the Cherokee Nation’s executive director, said in a statement last week that Warren had apologized to the tribe.

“We are encouraged by this dialogue and understanding that being a Cherokee Nation tribal citizen is rooted in centuries of culture and laws not through DNA tests,” Hubbard said. “We are encouraged by her action and hope that the slurs and mockery of tribal citizens and Indian history and heritage will now come to an end.”

Warren aides declined to comment to CNN on the apology last week.