UEFA, the European governing body, has launched an investigation into Pellegrini's comments and will determine in due course whether disciplinary proceedings should follow.
Pellegrini, speaking at a press conference to preview this weekend's Barclays Premier League game with Stoke, addressed each of his complaints.
Attempting to clarify his remarks about Eriksson's impartiality, Pellegrini said: "I felt from the beginning his criteria was not the same for both teams.
"I think he had a bad day - everyone can have a bad day - but I didn't say that intentionally he didn't give fouls for us or did give fouls for Barcelona.
"I said from the beginning it was not the same criteria. I repeat, a bad day, not dishonest."
With regard to Eriksson hailing from Sweden, where the league is not considered as competitive as in some of Europe's leading football nations, Pellegrini admitted he made a mistake.
He said: "To say because he was always refereeing in the Swedish league, and that maybe it was better for so important a game to have another kind of referee - it is another thing I didn't think.
"It is not an offence to Sweden or the Swedish people or referees.
"Sweden is a country that has a lot of good players, they have one of the best in the world in Zlatan Ibrahimovic and it can also have a good referee.
"I am sure this is a good referee because UEFA is always evaluating all the referees and if he is not a good referee, he is not in the UEFA staff.
"The thing I said in that moment doesn't mean what I think.
"I didn't say any serious accusation about Sweden, just that it was not the most important league in Europe and that is not an offence, I think."
FIFA's referees chief has come to the defence of Swedish official after he was accused by Manuel Pellegrini of favouring Barcelona.
Pellegrini accepts his side face a tough task against Catalans in their Champions League last-16 tie, but he is far from intimidated.
Manchester City host Barcelona in the first leg of their Champions League last-16 tie. Here is a look at some of the likely key battles.