Ronaldo, now 39 and playing at his sixth European Championship, has struggled at the tournament in Germany and his inability to find the net so far has raised doubts as to whether he still deserves a starting spot in Roberto Martinez's team.
"Regarding Cristiano, we are humans and he felt emotional when he missed the penalty. That is totally acceptable," Silva said on the eve of Portugal's quarter-final clash with France in Hamburg.
Portugal reached the last eight by beating Slovenia on penalties, but only after Ronaldo had a spot-kick saved by goalkeeper Jan Oblak in extra time - he did later convert his penalty in the shoot-out.
"You want to help the team and he felt he could have done better in that moment," Silva added of the missed penalty.
"In my opinion it's a very good penalty and a great save from Oblak. Then he cried for a bit which is normal, which is how humans deal with emotions sometimes.
"So I don't see any reason for people to discuss it. But obviously people will because that's the business."
Without a goal to his name at the Euros, the all-time men's leading international goalscorer with 130 strikes has at times appeared desperate, notably with the number of unsuccessful attempts he had from free-kicks against Slovenia.
"We don't complain about the criticism. It's for the good and for the bad. It's part of the job," Silva added in defence of his captain and the criticism of the former Real Madrid player.
"Everyone knows a little bit about football. When it comes to June and the World Cup or a Euros, everyone thinks they are a manager. We get that and accept that."
Meanwhile, coach Martinez suggested that Ronaldo might not necessarily get to strike a free-kick if the opportunity presents itself against France.
According to statisticians Opta, Ronaldo has converted only one of 60 direct free-kicks attempted at major international tournaments.
"The players practice in training. Cristiano and Bruno Fernandes are the two players who have the responsibility," he said.
"Sometimes it just depends on the profile, or the position, or the moment, but we are lucky to have two players of such a level."
