Despite having fallen out of favour at the Bernabeu, the 23-year-old has enjoyed an impressive campaign while on loan at Sevilla.
The left-back's form has led to interest from the Premier League, most notably from Chelsea, who are said to be in advanced talks with the Spaniard.
However, according to Italian journalist Gianluca Di Marzio, Napoli are also keen on bringing in the player this summer.
The report says that the Coppa Italia winners have already carried out scouting trips to assess the development of Reguilon, who is still in Europa League action with his temporary club.
In a bid to raise funds to boost their financial position, Real could agree to a sale for a fee in the region of £20m.