The Red Devils boss was said to be annoyed with the club's hierarchy for failing to push through a move 12 months ago for one of his top attacking targets.
United continue to be linked with Perisic, who starred for Croatia in their run to the World Cup final, and Mourinho admits that he wanted the 29-year-old in his squad.
"I wanted Ivan Perisic," he told Russia Today before the winger's goal in the 4-2 defeat to France in Sunday's final.
"He went from Croatia to Borussia Dortmund, then to Wolfsburg, then to Inter. I do not know why he did not come to Manchester United, I wanted him."