Real Madrid whinge about referee
Both hinted Undiano wanted Barca back in the La Liga title race by giving Gerardo Martino's men favourable decisions during El Clasico.
Lionel Messi's hat-trick led his side to the much-needed win in a match that included three penalties– two to Barca and one to Real – and a red card to Ramos.
Ronaldo believes Real are consistently mistreated by referees in El Clasico encounters, with the win moving Barca within a point of Atletico and Real (70 points each).
"We played against 12. It's always the same. They don't allow us. Maybe they wanted Barca back in the league," Ronaldo told reporters.
"I don't want to leave this inside of me and I'm not looking for excuses but the ref is not at the required level for a game like this.
"If Barca lost today they would have been out. After five years here (in Spain), I understand how things work.
"I have never seen Real Madrid favoured by the referees. I'm sure that no matter about all this, we will win the league."
Ronaldo was awarded the most controversial of the three penalties on 55 minutes, when he was clipped outside the area but fell inside to earn a spot-kick.
The 29-year-old converted to put Real 3-2 ahead but the game turned in the 63rd minute as Ramos was sent off after making contact with Neymar, as the Brazilian looked to put away a one-on-one chance.
Ramos felt the result was 'pre-meditated' and believes Neymar went down without contact, despite replays showing the defender's left leg catching the attacker.
"It's always the same. I didn't touch Neymar but there's no point talking about it, it changes nothing," he said.
"Everyone can see what happened. We could have got something from the game but got nothing.
"There are some things you can't fight against. This was pre-meditated.
"I stopped because I preferred 3-3 rather than a penalty and a sending off."