Nani is under contract at Old Trafford until the summer of 2014, but said that he would have to consider the interest that has been shown in him.
"I'm a United player but there has been some interest on my behalf," he told Abola, a newspaper in Portugal. "I will evaluate it and decide what is the most advantageous for me. A return to Portugal? Right now I don't know."
There has been interest from Arsenal earlier in the summer and more recently from Serie A side Inter Milan.