Manchester United yesterday handed Ibrahimovic a contract until the end of the season.
The Swede is out with a knee injury until December and is expected to be fit after Christmas.
But Mourinho refused to go into the deal when asked about Ibrahimovic’s return date, ruling him out of selection for the Champions League group stage.
“He will not be ready for the group phase of the Champions League, I don’t think there is any chance of that,” Mourinho said.
“I’m not thinking Zlatan to play any part of the group phase, hopefully he can play in the knockout phase but for that we need to finish top two.
“I don’t want to think about it, I don’t even ask, speak about it or with the medical team about it.
“He will be an extra man for us in the second part of the season. When I say second part, we say January after Christmas, when the transfer window reopens but I have no idea at all.
“It shows two things for me, it shows me the dimension of the player and the club.
“The player it would be very easy for him to say goodbye. He had success at Man United, goodbye. He doesn’t do that, he wants to follow his other dreams and play football at the highest level.
“And a club like Man United in my opinion has to show how big it is in details and this is a big detail of a player that gets injured with the Man United shirt, fighting for Man United. The club has to be there for him and I’m really happy with club and player.”
Ibrahimovic, 35, scored 17 goals in the Premier League last season before his campaign was cut short by a knee injury in April.
United decided not to extend his contract by a further year, meaning he was a free agent in July.
A move to AC Milan was mooted but Ibrahimovic had remained at United’s Carrington training ground to continue his recovery.
And yesterday he penned fresh terms at the club until the end of the current campaign.