Before reaching Jupiter and its icy moons, the ESA JUpiter ICy moons Explorer (JUICE) spacecraft will travel ∼8 years within the inner Solar System, entering the asteroid Main Belt (MB) twice. This is a unique opportunity to flyby and investigate at close range one or more asteroids, as previously done by other missions. In order to identify multiple asteroids as possible targets of opportunity for the JUICE cruise phase, we developed a new code, called Automatic Asteroid Search Toolkit (A2ST), which determines the minimum distance between the orbit of ∼140.000 asteroids and the spacecraft. From the list of potential objects ordered by range, we identify asteroid (1650) Heckmann and (223) Rosa as two objects of particular scientific interest. (1650) Heckmann is a ∼30 km-size inner MB member of the Polana asteroid family and it belongs to a taxonomical group (F-type) that has never been observed at close range. On the contrary (223) Rosa is an outer ∼80 km-size dark MB asteroid (X-type or T-type) whose origin is not yet fully understood. Indeed, it may be a collisional fragment of the Themis family or a primitive dark planetesimal that formed in the outer Solar System. The in-situ observation of both targets by the JUICE mission would widely expand the knowledge of the Solar System formation and evolution, as well as the compositional structure of the Main Belt, hence maximising the scientific return of the full mission.