A source has claimed that Jenner was struck on the head by a bottle when he tried to break up an argument between Lavigne and the other woman at the Roosevelt Hotel in Hollywood on Saturday.
Both Jenner and Lavigne suffered cuts and bruises in the scrape and sought medical attention after the altercation was broken up.
Lavigne later tweeted that she was not responsible for causing a fight and insisted that violence is not the way to solve problems.
The 'Complicated' singer wrote: "I don't fight. I don't believe in it. To clear things up I got attacked by 5 people last night out of nowhere. Not cool. My face is f**ked.
"As in black eye, bloody nose, hair ripped out, scratches, bruises and cuts. So not OK to be abusive to others. Violence is NEVER the answer."
Jenner also took to Twitter following the scuffle, writing: "Interesting Saturday night, just got out of the hospital with a new scar on my face."
Lavigne recently denied that she is expecting her first child and added that she found the pregnancy speculation very "insulting".
The singer's fourth studio album Goodbye Lullaby hit the top 10 of the US and UK album charts earlier this year.
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