The 35-year-old is well ahead of schedule on his return from a long-term injury, which he sustained during the Red Devils' Europa League quarter-final tie with Anderlecht in April.
Ibrahimovic has provided positive updates during his rehab process and was rewarded with a new one-year deal at Old Trafford in August, having seen his initial 12-month deal expire during the summer.
Mourinho is happy to play the waiting game when it comes to getting the ex-Sweden international back up and running, though, telling reporters: "I think we need him. We wait for him, but with patience. He has to be patient.
"He doesn't have to be emotional and he doesn't have to try to make crazy things to improve quicker in his mind. Because I know that his desire is to improve quicker. So [he must be] calm – [take things] step by step. We want him, but we want him in his best condition."
Ibrahimovic scored 28 goals in all competitions for Man United in his debut campaign in English football.