The Uruguayan has notched 18 goals in 21 appearances this season and is believed to be on the radar of a number of clubs across Europe.
However, his £52m release clause has been a stumbling block in negotiations, with Partenopei president Aurelio de Laurentiis unwilling to sell cheaply.
Meanwhile, Roberto Mancini's strikers have underperformed this season, and the Italian is keen on freshening up his attacking options.
According to the Daily Mail, the Citizens are preparing a summer raid for the 25-year-old hitman, who moved to Naples from Palermo in 2010.
Real Madrid and Paris Saint-Germain are also understood to be interested.