The Chilean star has been linked with a move this January with Italian and European champions Inter as well as Spanish powerhouse Barcelona said to be in line along with Premier League giants Manchester United and Chelsea.
Udinese have continued to stress that they will not sell the 22-year-old this month with president Pozzo dismissing reports of a January transfer, and now Guidolin has done the same.
The Udinese coach told Italian TV station Rai Due, "I know Udinese is a serious club. The club have reiterated that Sanchez will remain at Udinese until the end of the season and I have no doubts on this matter.
"Of course, if a tempting offer would arrive it would be right for the club to evaluate it but I believe that Alexis can still grow from here on until the end of the season if he stayed with us.
"After that, he is destined, considering the quality he has shown for some time, to join a top club.''