Mourinho resumed at Old Trafford in July, eight months after he was dismissed by Chelsea for the second time.
His dismissal followed a disastrous Premier League title defence and what technical director Michael Emenalo described as “palpable discord” between players and management.
While Chelsea struggled, Willian was one of few reliable performers in Mourinho’s final season, scoring five goals and registering six assists as well as being voted the club’s Player of the Year.
Reports in England last summer suggested that the pair were set for a move to United.
Willian told Globo Esporte, “Concrete [offers], I have no idea. But Manchester United were interested in me, since Mourinho is there now.
“Other clubs I am not aware, but there is always something on the internet. In any case I am happy that there are clubs who admire my work.”
The forward has continued to perform do well under Antonio Conte despite fighting with Pedro Rodriguez for a place in the starting lineup.