Despite netting 21 goals in 17 league games for Los Blancos this season, the Portuguese winger has been targeted by the Spanish media and supporters.
"We are talking about a striker and a striker should be compared with those of other teams," Mourinho told reporters.
"But if you want to compare, do you have statistics of the others?
"We're talking about the Golden Boot winner here. The only one who has scored more goals than him is a player from Estonia (Aleksandrs Cekulajevs)."
Madrid, who are currently top of the La Liga table, travel to Mallorca on Saturday.