"The comments are frivolous and shouldn't be taken seriously... Neither Mumbai nor Vidarbha will be separated from Maharashtra," the chief minister said here.
"Unity is our strength," he said.
Meanwhile, Shiv Sena activists held protests outside De's house in South Mumbai today.
In the wake of bifurcation of Andhra Pradesh, De had tweeted that "Maharashtra and Mumbai??? Why not? Mumbai has always fancied itself as an independent entity, anyway. This game has countless possibilities".
The tweet has raised hackles of Shiv Sena and Raj Thackeray-led Maharashtra Navnirman Sena (MNS).
De has refused to apologise or withdraw her comments.