The German completed a transfer deadline day move to Arsenal for £42.5 million and Mourinho this week compared his former player to all-time greats Luis Figo and Zinedine Zidane.
“Ozil is unique, there is no copy of him, not even a bad one,” he said.
“He is the best No.10 in the world. He made things easier for me and his team-mates with his vision of the game and the decisions that he made.
“Everybody loves him and you can see a bit of Figo and Zidane in him."
Arsenal made an approach for Ba on the final day of the summer transfer window and looked set to take the Senegalese striker on a season-long deal, but their signing of the 24-year-old Ozil resulted in Mourinho personally blocking the move.
“I did not accept Arsenal’s offer for Demba Ba because added to their signing of Ozil, they would have been title contenders," he said, in quotes reported by various national newspapers.
Wenger had prioritised a new striker all summer, but, with Olivier Giroud his only fit and recognised striker available, he was forced to call off the proposed sale of Nicklas Bendtner.