The site reports that Kardashian, 31, was on her way inside a SoulCycle studio in Beverly Hills, California, when Odom appeared and began screaming at her, demanding that she speak to him.
Kardashian reportedly kept walking and Odom eventually grabbed her arm.
"Get off of me, get off of me," she reportedly screamed. "Stop! Stop!"
According to the site, an eyewitness asked if Kardashian wanted them to call the police, at which point Lamar screamed, "You're not going to call the cops on Lamar Odom."
"How did you know I was here?" Kardashian reportedly demanded Odom, to which he didn't give a clear answer.
The site reports Kardashian then got inside her car and drove away. A source tells PEOPLE that Kardashian had to change her phone numbers several weeks ago because Odom would not stop calling.
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The Keeping Up with the Kardashians star and Odom wed in 2009 just one month after meeting. After he relapsed with his substance abuse problems and cheated on Kardashian, she filed for divorce in December 2013. The exes finally signed the divorce papers July 21.
Most recently, Kardashian opened up about her painful split from Odom in an interview with Complex magazine for the August/September issue.
"Lamar is genuinely one of the best people I've ever met, and everyone says that when they meet him. I think Lamar's going to always be that person [for me] but that's what made it so special," she told the magazine. "I definitely miss it, and there's times I'll get so sentimental and so sad, but this had to happen for some reason. I'll figure it out over time, someone will give me that answer eventually."
Kardashian is now seeing NBA player James Harden. The two have worked out together at Cycle House in West Hollywood.
Kardashian and Odom's reps could not immediately be reached for comment.