The defender, on loan from Porto, grabbed Inter's equaliser in the early stages of the second half when he swept home Mauro Icardi's knock-down from close range.
It restored parity after a disappointing first half in which Juan Jesus was penalised for handball in the area and Mauricio Pinilla coolly converted the resulting penalty.
And despite dominating play, Inter found Vlada Avramov in inspired form. The Cagliari goalkeeper saved excellently from Rodrigo Palacio and Fredy Guarin, while Icardi headed against the crossbar in the final minute.
The result ensured Inter extended their unbeaten home record to 10 games since Roma won at San Siro in October, but the Portuguese international felt the penalty decision was harsh and criticised what he perceived as a lack of ambition from the visitors.
"We played well, especially in the second half," Rolando told Sky Sport Italia. "We conceded a goal from a penalty that wasn't.
"I'm disappointed but that's football.
"Serie A is difficult and after the penalty they didn't have any other chances to score and we dominated the second half.
"It's tough to play against teams who always put 11 men behind the ball."
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