The Argentinian moved to Barca last January for £8m from River Plate and made an immediate impact.
However, Henrik Larsson's return to fitness, the emergence of 18-year-old sensation Lionel Messi and the continued excellence of Samuel Eto'o have meant the 21-year-old Lopez has made just one sub appearance this season.
With the World Cup coming next summer, Lopez is looking for a loan move and regular first-team football in order to try to force his way into Argentina's squad.
The Daily Mail claims City will open talks this week with the player, who has also been targeted by West Ham, Real Betis and Real Sociedad.