The 23-year-old has also been targeted by Arsenal after impressing in his first season at De Kuip following a move from Heerenveen last summer.
Janmaat's representative Karel Jansen said that he has spoken to the Nerazzurri, but added that they are yet to make a formal offer.
"Yes, Inter and I have talked and I can confirm that the club is on the player," he told FC Inter News.
"However, there is no concrete negotiation at the moment as they have only asked for information of Daryl.
"What is going to happen in the future? That I do not know."
The Dutch international made his debut for Oranje in a 2–0 win over Turkey in September.