Inter president Massimo Moratti last week said referees were not acting in good faith after Atalanta beat Inter 4-3 at San Siro with the help of a highly controversial penalty.
On Sunday, Cagliari got off the mark with another doubtful penalty, won and converted by Chilean forward Mauricio Pinilla, but Stramaccioni, though critical, was more diplomatic.
"I believe in sport and I believe in values... the referees are making mistakes and they are repeating them," he told RAI television. "The penalty was completely non-existent."
He added that Cagliari should have had a player sent off for stopping Tommaso Rocchi when he had a clear scoring chance.
Inter, who have been decimated by injuries with striker Diego Milito out for the rest of the season, dominated the game until midfielder Walter Gargano went off injured in the 53rd minute.
It got worse for Inter when Yuto Nagatomo came on in the 67th minute and limped off seven minutes later.
"Until Gargano was injured, we were much the better team and we had created three clear chances," said Stramaccioni.
"Then we lost a player with individual and tactical value."
"It was yet another injury in yet another incredibly jinxed season."
Inter have slumped to seventh in Serie A with 50 points from 32 games and four defeats in their last five games have virtually ended their chances of qualifying for the Champions League next season.
Their next match is on Wednesday when they host AS Roma in the second leg of their Italian Cup semi-final, trailing 2-1 from the first leg.
