The 21-year-old, who is currently putting the finishing touches to new N-Dubz album Against All Odds, criticised Jackson for her negative opinion on commercial urban music.
"She basically said all women who do urban music and UK R&B dress too sexily, so when I heard that, I was insulted," she told Heat.
"I'm not one to bitch. Even if I don't like someone, it's not my style to do that. Then I hear that she's dissing everyone and saying the music is crap. I mean, that's just rude.
"Where was she brought up - in a barn? You don't talk about other people's jobs like that. It's just wrong. I think she's a tw*t."
Asked who would win in a fight between the pair, Tulisa insisted that she would come out unscathed.
"Oh, definitely me. She wouldn't last five minutes with me. I've been sparring with Fazer and Dappy since the age of five," she said.
"I don't have to tell you the amount of black eyes I've given. No doubt about that. She don't wanna go there."
Jackson has previously claimed that Tinchy Stryder is "overrated" and The X Factor "f**ked up". Meanwhile, N-Dubz caused controversy last month after branding JLS "manufactured".
N-Dubz release new single 'I Need You' on November 2. Their album Against All Odds follows on November 16.