Lopez's deal runs to 2027 and he is this season Valencia's top scorer with seven goals.
He told Marca: "Talks have started, but there are other priorities before renewals: finishing the season well, saving the team, and the rest will come.
"I'm happy here in Valencia, very happy. It's my home, it's given me everything. There's still time to talk; I have two years left on my contract."
On his improving form, Lopez added: "The only thing that's changed is that the goals are coming in now. The previous (Ruben) Baraja coaching staff and the current one have told me that a season is very long, there are ups and downs, and I was lacking in numbers.
"Now, in the last month, they've all come in at once. It seems that these numbers make you have a better season, but everyone told me that the season is remarkable, and I'll stick with what they tell me. If the goals are coming, so much the better."