Barcelona were 10 points behind Madrid earlier in the season, however, and Iniesta has not given up hope.
"Madrid are still the leaders. They have the advantage and a game in hand. Things have changed, but we will keep fighting to add three points with every game," the 27-year-old told reporters.
"That is what we want until the end. Madrid can win matches like the one on Wednesday. But these derbies are always very intense."
Real face Atletico Madrid on Wednesday.