The Portugal international only penned a new long-term contract at Old Trafford in September, with David Moyes making the securing of his services a top priority.
Nani has struggled for form and fitness since then, but returned to action off the bench in Saturday's 4-0 victory over Newcastle United.
He had, however, been a bit-part player prior to picking up a knock - restricting him to just five Premier League starts.
Transfer speculation, which first emerged in January, has now resurfaced, with Fiorentina reported to be leading the chase.
Nani's agent is reluctant to be drawn on potential destinations for the 27-year-old winger at this stage, with financial factors to take into consideration, but admits that all options will be considered at the end of the season.
Pastorello told Violanews.com: "Nani is a very important player and at this time the only thing I can say is that he is likely to leave Manchester.
"The problem for Fiorentina and other Italian clubs is the player's salary. But we will evaluate all bids.
"Our relationship with United is great. Fiorentina have to speak with Manchester United about Anderson and maybe there will be an opportunity to talk about Nani too."