Benfica winger Prestianni denies 'ugly' racism claims
The 20-year-old Argentinian was accused of making a racist insult towards the Brazilian in February, while covering his mouth with his shirt.
The referee stopped the match for 10 minutes and the player was subsequently suspended for the second leg by UEFA, which opened an investigation.
If UEFA finds he abused Vinicius then he will be banned for at least 10 matches.
Real Madrid progressed 3-1 on aggregate to reach the Champions League last 16.
Prestianni told Argentine broadcaster Telefe that missing the second leg in Madrid "hurt a lot" and denied making the insult.
"I was thinking about my father, my mother, my grandparents, about the fact that so many things were being said that don't reflect who I am and that didn't happen," he said in his first interview since the incident.
"It's ugly and it hurts a lot."
He said he was "very grateful" to his club and his teammates for their internal support, and said that his coach, Jose Mourinho, was "a phenomenon".
Mourinho was criticised after seeming to indicate that Vinicius provoked the alleged abuse with his goal celebration after scoring in the first leg.
The Benfica coach later clarified his position, assuring that if the accusations of racism were confirmed by the investigation, the Argentine would never play for him again.
Prestianni was called up by Argentina for friendlies played in the past week.
"I work day in, day out to make this opportunity arrive," the winger said, adding that his greatest dream was to play in a World Cup with the Albiceleste.