Ronaldo, 27, scored two goals in the 3-0 drubbing of Granada at the Santiago Bernabeu, taking his goals tally to 150 in 149 appearances, and becoming the ninth highest goal-scorer in the history of the club.
"I am sad and the club knows it, that's why I didn't celebrate the goals. The people in the club know why," Ronaldo said.
Ronaldo was substituted during the 64th minute by striker Gonzalo Higuain after suffering a nasty collision with Granada defender Borja Gomez.
However, Ronaldo refused to explain the exact reason for not being happy at the club. "I'm not going to say anything else, people know why," he said.
The former Manchester United winger, who signed with Real for a record breaking £80 million, also denied that he was angry after Barcelona's Andres Iniesta beat him to win the UEFA Player of the year award.
"It's nothing to do with him, Iniesta deserved it," he said.
However, despite the injury, Ronaldo is set to play with Portugal for the 2014 World Cup qualification round against Luxembourg on Sept 8 and 12.
"I'm fine," he said. "I am going to Portugal to see if I recover in the next couple of days because I want to play those two games, which are so important for the team."
Portugal are placed in Group F for the qualifiers along with Russia, Northern Ireland, Luxembourg, Israel and Azerbaijan.