But English referee Michael Oliver pointed to the spot in the 93rd minute after Mehdi Benatia prevented Lucas Vazquez from executing a close-range finish with a clumsy challenge from behind.
The Galacticos are on course for a third successive UEFA Champions League crown, even after Wednesday's 3-1 loss to Juventus, as Real progressed 4-3 on aggregate to book their place in the semi-finals.
"I do not think of playing without Cristian, we have him and we are happy", Zidane said on Tuesday.
The penalty came as Vazquez was in position to score in front of the goal after Ronaldo headed down a cross into the area.
Ronaldo admitted he had to calm himself down before stepping up and slotting home his 120th Champions League goal, followed by a shirtless celebration.More news: Red Sox outfielder Mookie Betts exits game after play at plate
He said: "I knew we would be up against it, but I didn't expect what happened in the first minute".
"In football, nothing is given away, you have to fight until the end".
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At half time Real Madrid coach Zinedine Zidane brought on Marco Asensio and Lucas Vasquez for Gareth Bale and Casemiro, potentially in an attempt to reduce the impact Juve's wide players were having in the match.More news: Warriors 'flip the switch' in Game 1 rout of Spurs
Isco had a goal correctly disallowed for offside soon after as Real pushed for a killer fourth goal in the tie, with Buffon blocking well at his near post from Isco soon before Juventus' second.
" Everyone has their own opinion on whether it was a penalty or not, I'm not going to discuss that, but I'm angry that people are talking of a robbery."
They also claimed the referee "punished" them with a controversial penalty and the sending off of Buffon.
Paying tribute to star man Ronaldo, "Zizou" enthused, "Cristiano (Ronaldo) is used to these situations".
Real went on to win the competition in each of those years and defender Dani Carvajal said those experiences helped his side keep their composure after they fell 3-0 behind after 60 minutes against Juve.More news: GlaxoSmithKline (LON:GSK) Receives Buy Rating from Liberum Capital
"We could've scored five or six goals, so we ought to be proud". They played well but we were just average, the difference is we kept believing until the end. We're in the semi-finals.