Footage shows the Zoey 101 star and mother-of-one marching behind the kitchen counter and picking up the knife, as one of the restaurant employees looks on.
TMZ reports that the incident occurred when Jamie Lynn was visiting the health food wrap chain for a late night snack and her female companion was allegedly hit with a bottle.
The shop employee was seen on the phone, presumably calling the police, as the diminutive star waved the knife around.
TMZ claims that when officers arrived, Jamie Lynn's friend did not want to press charges, so no arrests were made.
Hours before the fight, the mother-of-one shared a picture of her and a friend posing on their low-key night out.
Jamie Lynn, who was was dressed down in a denim jacket and a patterned scarf, captioned the shot, 'Happy Birthday @brandiblair22 !!! #nofilter'.
The star returned to the spotlight this year after taking time out to raise her daughter.
She famously shocked fans in 2007 by revealing she was pregnant aged just 16, which drove her blossoming career as a Nickelodeon actress to a halt.
That same year, her then 25-year-old sister Britney infamously hit a photographer's car with an umbrella during a high-profile public breakdown.
Jamie Lynn, who married businessman Jamie Watson in March 2014, released her first album of country music anthems called The Journey this spring.
She says her superstar older sibling has been a guiding force all her life and encouraged her to pursue her passion for music.
"There's such a big age difference between me and my sister that I think [she] almost was like a second mom," Jamie Lynn told Access Hollywood.
"She's so supportive and she's so encouraging of me and she's like my biggest fan... She's always had my back."
- Daily Mail
