Speculation has gone into overdrive in the last week after news emerged that the 37-year-old was looking to leave Old Trafford in order to challenge for more trophies.
Ronaldo is yet to return to the club following his summer break, with United citing 'family reasons' for his decision not to travel with the squad on their pre-season trip to Thailand and Australia.
However, this comes after reports that Chelsea are considering a move for the Portuguese star and could offer him Champions League football, something that's not available with the Red Devils this term.
United have insisted that Ronaldo will not be sold this summer, something that was backed up by Ten Hag during a press conference from their pre-season tour to Bangkok.
In a series of short answers, Ten Hag explained: "He's not with us and that's due to personal issues.
"We are planning for Cristiano Ronaldo this season and so, that's it. I'm looking forward to working with him.
"I spoke with him before this issue came up. I had a conversation with him and had a real good talk.
"[What was said] is between Cristiano and me. All I can say is we had a really good conversation together."
Asked how he can make Ronaldo want to stay, Ten Hag added: "I don't know. He hasn't told me this.
"But when I say Cristiano is not for sale, Cristiano is in our plans and we want to have success together."