Ramos was booked in just the 10th minute of the Copa del Rey semi-final first leg at Camp Nou and was perhaps fortunate to escape a second yellow for a foul on Arthur and, later, an incident involving Luis Suarez.
While Pique said referee Antonio Mateu Lahoz performed well, he thought Ramos should have seen red.
"In general, he has made a good match," he told reporters.
"It was a red card for Sergio, but what can we do?"
Barca came from behind at home as
Pique was happy with what he saw from the 31-year-old superstar and he hopes Messi is ready to go against Athletic Bilbao on Sunday.
"I've seen him very well, fast. He has not felt the discomfort he had and it's good news," he said.
"We hope to have him for the San Mames match and help us."
The result keeps alive Real's hopes of reviving their ailing season with cup glory, though they remain eight points behind the champions in the league
The European champions have already been beaten six times in the league, twice the number they lost during the entirety of their last La Liga title success under Zinedine Zidane in 2017.
The two teams will meet again at the Bernabeu for the second leg on February 27 for a place in the final.
Before then, Real are back in action away at Atletico Madrid on Saturday where they will look to cut the gap to Barca to five points ahead of the champions game against Athletic Bilbao on Sunday.