The French club were strongly linked with the Gers man.
However, the signing of Jonathan David from Gent means they have acquired a promising young striker.
While he was coy on the matter, Lopez indicated Morelos may not be a priority now.
"Obviously Morelos is a good player," Gerard Lopez told BBC World Service.
"He's part of a list of players we've looked at, but we've made a move for another player, so we have something like 11 offensive players for four spots now.
"He's a player who is extremely effective and at this stage we're watching, but nothing's done."