The 22-year-old was linked with a number of big European clubs over the summer, but a deal failed to happen.
"Manchester City were interested a few days ago, but nothing was ever close," the Frenchman told A Bola.
"I'm a Porto player and I feel good here. I have no problem with this issue. I am fine here and focused on what we can do this season."
Mangala joined Porto from Standard Liege in summer 2011.