The 26-year-old rapper wants Styles to stay away from Grande, and hates that they have stayed in touch since working on the song 'Just A Little Bit of Your Heart' together, reported Ok! magazine.
"Big Sean doesn't like it that Harry's been wooing her. He wants Harry to back off and leave Ariana alone," a source said.
The couple's romance, which began two months ago, came as a shock to fans as Big Sean - whose real name is Sean Anderson - only ended his five-month engagement to 'Glee' actress Naya Rivera in April this year.