The Dutchman was quick to quash the claims made by Pique recently, where the defender expressed his opinion that referees favour Real Madrid.
"Those are [Pique's] words. I can only comment on this year, not on previous seasons," Koeman told the press.
"There are decisions in which we have had no luck, but I don't think they are against us. They are decisions of the referee and also VAR.
"I always think that the attitudes of the referees are honest. They give what they see and are not in favour of any team."
Ahead of meeting Real Betis on Sunday, Barcelona's form in general has seen an upward turn in recent weeks, and Koeman could be seen celebrating passionately from the touchline in midweek against Granada.
"I can't deny that the other day I was very happy after the game. I don't know for how long. Today it's sunny and tomorrow it may rain," he said.
"I really liked the game the other day, but tomorrow is another game. We have to prove ourselves yet again that we are on the right track."
Barcelona are now second in the table, ten points behind leaders Atletico who also have a game to spare, but Koeman hasn't given up on the title.
"There is always hope," he stated. "There is a big gap in terms of points and [Atletico] have played a game less.
"We have to keep winning games but it's very difficult. We are hopeful because we have improved in many aspects."