Juventus forward Ronaldo scored twice in Saturday's 4-0 away win, earning a 9.1 FC Rating in an impressive performance for the Italian champions.
The fine display came three days after he missed a penalty as Juve struggled to a 1-1 draw at home to Atalanta.
Pirlo explained after the Parma victory that Ronaldo's frustration had been clear to everyone in the Juve camp.
But the head coach felt it simply showed how much the 35-year-old cares about scoring goals and that he particularly enjoys it when they come from open play.
"Ronaldo was angry with himself for having missed the penalty," Pirlo told Juve's website.
"But we [only] had a few days to think about it and he [quickly] showed how much he cares about scoring goals, even better when [they come] during open play.
"We were not happy with Wednesday's result, but the performance was good.
"We needed to score and have a team win - we did it while playing good football."
The Portugal International has scored 10 goals in his eight Juve games across all competitions over the last month.
Ronaldo leads the Serie A scoring charts with 12 in nine appearances (eight starts), two clear of Romelu Lukaku and Zlatan Ibrahimovic.
His 7.8 FC Rating for the league season so far is second only to Ibrahimovic (8.4) among players to feature for at least 500 minutes.
Alvaro Morata (9.5 FC Rating against Parma) also shone on Saturday, scoring once and recording two assists.
It was the sixth time the Spain striker has been named man of the match in all competitions this season.
Pirlo added: "We are not surprised [about Morata]; we knew he is a great player and when he is [feeling] well, he can do anything.
"We are in a good moment, I like how we attack the opponents when they have the ball, we are growing.
"The right spirit is here, but we are only at the beginning and we will have to have this attitude in every match."