The Barclays Premier League rivals are both keen on the wayward 19-year-old, but the European champions are understood to be seeking £30million for a player who has been on the fringes of a hugely talented side.
"Balotelli is priceless. At this time, he and (Brazil right back) Maicon are not on the market," said Branca.
"When and if there are requests we will kindly examine them but they are not on the market.
"The interest in Balotelli from both Manchester clubs is real and very strong, but has not reached an official offer."