The Santiago Bernabeu side would have moved to within two points of leaders Atletico and one point clear of Barcelona ahead of next week's encounter between both of their title rivals, but Sunday's results mean they will finish second at best now.
"We are disappointed that we lost La Liga. This is the first competition this season we will not win and that's a deception," Ancelotti stated at a press conference.
"We missed several important players, so it was not easy to prepare for this match. We gave away two easy goals, but we tried to get back in the game after that.
"There's no denying that we haven't done well in the past few games, but I don't think we gave away La Liga. We lost a bit of intensity after the Champions League semi-finals and that has cost us dearly.
"We have to look toward the future now, recover from our efforts and prepare for the final."
Real Madrid meet Espanyol in their last league game of the season before they take on Atletico Madrid in the Champions League final on May 24.