Musharraf's remark appeared designed to end speculation that he could strike a deal with Bhutto to broaden his fragile support base.
Bhutto, who leads the popular Pakistan People's Party, went into exile in 1998 over corruption cases pending against her and her husband.
Sharif was sent into exile in December 2000, a year after Musharraf toppled him in a bloodless coup.
The two politicians, who each ruled Pakistan twice between 1988 and 1999, have repeatedly said they would defy Musharraf and return home to lead their parties in elections due before next year.
Their hopes got a boost from an ongoing judicial and political crisis sparked by Musharraf's removal of the country's chief justice.