The 20-year-old Spaniard feels Emirates Stadium is the right place for him to be now, having once again rejected the overtures from Real Madrid this summer.
However, Wenger insisted: "I did not allow Fabregas to talk to anybody. He denies he did.
"If you can get the statement he has done that and that Real Madrid, more than ever, has done that, then we will sue Real Madrid.
"His agent might have spoken to Real Madrid.
"But Real Madrid are not entitled to do it without our permission.
"You expect other clubs to behave in a fair way when you have players under contract."