Reports in the English media claim United manager Louis van Gaal is determined to sign Strootman, who is still recovering from a long injury lay-off, despite Roma placing a 75 million euro (£60m) price tag on the 24-year-old.
Speaking to Sky Sport Italia prior to the Giallorossi’s home game against Cagliari, Roma director general Mauro Baldissoni said Strootman was not for sale.
“We can’t wait to have him back playing because we miss him, he’ll be back soon,” said Baldissoni when asked about United’s interest.
“We’re proud to have him in the squad and he’s not for sale.”
Roma, last season’s runners-up, have returned to the Champions League for the first time since the 2010/2011 season and began their Group E campaign with a 5-1 rout of CSKA Moscow in midweek.
Baldissoni added: “The Champions League was our objective, we’re happy to be back in the competition playing against the big teams. Thankfully, we’ve had a positive start.”