He has scored 26 goals this season and is showing no signs of slowing down despite his advancing years.
Amid speculation he is holding out for a two-year contract extension at United, Ibrahimovic spoke warmly of the club and Mourinho's influence on his performances.
The Swedish striker arrived at Old Trafford on a free transfer from PSG last summer and many questioned whether he would be able to cut it in the Premier League in the latter stages of his career.
While Manchester United are mulling over the contract, Zlatan's agent Mino Raiola is in talks with Major League Soccer (MLS) side LA Galaxy.
Speaking to BBC Sport, Mourinho said: "Zlatan is not a surprise for me".
"Because of the professionalism, the training and his commitment to the club".
"It's not personal what I have". A lot of United's success has revolved around him.
"First he called me every day to have me and from one day to the next I didn't play anymore", he said.
"There has to be a dip at some point". And a player of Zlatan's status wouldn't want to miss out on big matches, and under the circumstances, Jose Mourinho will have a tough time to hold on to the Swede global.
Ibrahimovic is, however, available to play against Rostov in the Europa League on Thursday.
He missed the 1-0 defeat by Chelsea in the FA Cup on Monday, and will be absent for United's next two Premier League games against Middlesbrough and West Brom.
"The bad is that at times maybe his form hasn't been as good as it was last season".
"There's potentially always going to be a fall in a young player". He can have confidence knowing he will play.
Seeded North Carolina ready to run vs
Bettors should not be surprised to see a similar result here, as the Tar Heels are too talented to let the Razorbacks hang around. The Tar Heels (28-7) led by 25 points at halftime, and cruised to their third biggest margin of victory in tournament history.
In theaters this weekend: 'Beauty and the Beast'
The film was originally scheduled for release on Thursday, but was held back after the board ordered the scene to be cut. It might have just been that the other characters were so much more entertaining that Watson's Belle got washed away.