The Armenian was one of Mourinho's first signings in the summer of 2016 but inconsistency has blighted the playmaker since he joined from Borussia Dortmund for £26.3million.
His name has been littered in gossip columns regarding a potential exit this month, and Mourinho has refused to rule out the possibility of him moving on.
"My approach to players is that every player has a price," Mourinho said when asked directly about whether Mkhitaryan would stay.
"It doesn't matter who he is. It doesn't matter the level. It doesn't matter the prestige, the status. I think every player has a price.
"And I am not the kind of blind manager...blind in the sense of, this player is untouchable, can never be sold. I think every player has a price.
"So when the transfer window is open, it's also open for any club that is interested in our players. Then it's up to us to make the decision: yes or no. It's up to us to decide what we think is the right price.
"But Mkhitaryan played the last match in the FA Cup and probably will play the next one (against Stoke). He's a little bit the same in relation to other players that are involved in this gossip of the transfer market.
"He is our player and a very good player. So Saturday (he is) training, then Sunday (he is) selected and Monday (he will) play."