Zeki Celik gave Roma the lead before Porto found a scrambled equaliser through Francisco Moura. Bryan Cristante was also sent off midway through the second-half.
After the playoff first-leg, Ranieri fumed: “I thought it was a great game of football, we came here to win, we played really well and I am happy with the performance from these lads.
“What I cannot stand for is how it is possible that Mr Rosetti, who the whole world knows is an upstanding individual, thoroughly honest, send to Oporto a referee who in 22 games he officiated the away teams managed only nine draws? All the others were home victories.
“You are upstanding, but do you know this? It’s a fiery atmosphere, the crowd blows and he moves in their direction, and you assign him to this fixture? I don’t understand why.”
Ranieri continued: “He was going around promising cards to some, giving them to others. In my view, he was waiting for something to happen inside the penalty area so he could give them the victory.
“It was clear. This is why the lads were irritable, because you cannot do something like that.
“Did I perceive he was predisposed? I had warned the players, do not protest ever! Because this is how he officiates. It is the referee who does his job, he is convinced that he did it well, but eight yellow cards for us, a red… Some were fair, don’t get me wrong, but you cannot go around irritating players like this from the get-go.”
Ranieri admits at the final whistle he didn't want any interaction between his players and Stieler.
“I also didn’t want them to even salute him. He did not deserve a salute,” said Ranieri. “Seeing something like this on an international pitch… It’s done now, we move on.”