"Anyone who knows me knows how much I love Britney and am rooting for her always," Zegler tweeted on Jan. 17. "While I meant no disrespect whatsoever, I should have thought about how this could be perceived, and I'm so sorry for upsetting or disappointing anyone."
In a follow-up tweet, she added, "This is not a situation to be taken lightly, and we should all be lifting Britney up in this pivotal time. Thanks for hearing me out, and a big thank you to all who held me accountable."
Zegler's video came a few days after Britney, 40, slammed her sister Jamie Lynn, 30, in a series of tweets in response to Jamie Lynn's interview with ABC News.
During the sit-down, Jamie Lynn alluded to a claim in her memoir, "Things I Should've Said," that Britney once took a knife and locked the two of them in a room together.
"Jamie Lynn... congrats babe!" Britney tweeted on Jan. 14. "You've stooped to a whole new level of LOW... I've never been around you ever with a knife or would I ever even think to do such!!! The only knife I ever saw you with at home was cutting the biggest pieces of squash I ever saw in my life, and it was way too big for me to cut... So please, please stop with these crazy lies for the Hollywood books!!!"
Britney added, "NOW and only NOW I do know only a scum person would make up such things about someone. I'm actually very confused about you making that up because it's honestly not like you at all !!!!"
Amid their war of words, after Jamie Lynn seemed to respond later that day with a cryptic post mentioning "the truth," it also seems like the sisters may be heading towards a possible reconciliation. On Jan. 16, Britney shared another statement to social media addressed to her younger sister, explaining that she said "some harsh things" and told Jamie Lynn, in part, "Just know I love you."