The Finn, who was ruled out of Lotus's final two races of the campaign due to a back problem, decided to leave the Formula 1 outfit in favour of a return to Ferrari for the 2014 season.
When asked on Finland's MTV3 if Raikkonen has now been paid in full, Lopez said: "Not entirely. Some of it, yes, we reached an agreement on the payment in Abu Dhabi.
"There have been delays, but the amounts that I have heard [in the media] are completely ridiculous. I will not go into detail, other than to say that the amounts we owe are not big. We will pay, just as we always have done."
Raikkonen spent one year with the team.