The 19-year-old has forced his way into Rudi Garcia's first-team plans at Stade Velodrome this term, making 22 starts in all competitions.
Barcelona have been linked with a move for the midfielder but he pledged his future to Marseille only last month by signing a new four-year contract.
Lopez has now said that he could have moved to Anfield in the 2014-15 campaign as a long-term replacement for Brazil star Philippe Coutinho, who was himself linked with Barca before renewing his own contract in January.
Confirming concrete interest from Liverpool he told L'Equipe: "They said to me: 'In five years, you'll be playing in Coutino's spot'. They approached me in a positive way. I even met Steven Gerrard at the stadium after the game.
"I wanted to go there but I also wanted to stay at OM. Leaving like that, at that age - even with your family - is very tough. I noted that they had a squad of 30 youth players, not to mention the first-team players. You really have to be mentally prepared."