Do you have a proof that the constraint is convex (some kind of second order cone thing?)? I will presume it is non-convex unless you show otherwise, in which case the non-convex designation will be removed (edit: the non-convex designation has now been removed).
Per the CVX Users’ Guide and Why isn’t CVX accepting my model? READ THIS FIRST! , you are not allowed to enter the constraint as you have. And if it is somehow convex, reformulation will be required for entry into CVX.