Ramos was booked in just the 10th minute of the clash at Camp Nou and was perhaps fortunate to escape a second yellow for a foul on Arthur and later an incident involving Luis Suárez.
While Piqué said referee Antonio Mateu Lahoz performed well, he thought Ramos should have seen red.
"In general, he has had a good match," he told reporters. "It was a card for Sergio, but what can we do?"
Barça came from behind at home as Malcom cancelled out Lucas Vázquez's opener, with Lionel Messi only able to come off the bench after battling a thigh injury.
"He (Messi) looked really good to me, fast. He has not felt the discomfort he had and it's good news," added Pique. "We hope to have him for the San Mamés match and help us."