The 22 year-old is the Bulgarian Championship's leading scorer, having struck 17 goals for Botev Plovdiv in just 14 games.
Hristov's agent, Georgi Gradev, said: "He's a very interesting player. Kaiserslautern tried to sign him in January, but in the end it came to nothing. Recently, however, Real Madrid have scouted him and expressed their full interest in him. But still nothing is defined."
Real posted scouts for Botev Plovdiv's clash with Lokomotiv Plovdiv last week.