Roma midfielder Seydou Keita claims racist remarks made by Pepe earlier in his career were the reason behind his midweek confrontation with the defender.
Prior to Roma's International Champions Cup clash with Real Madrid, Keita threw a water bottle at Pepe after refusing to shake his hand, sparking a coming-together between both sets of players on the pitch.
Following the incident, Keita took to his official Twitter account to state that Pepe had racially abused him during his playing days with Barcelona, writing: "1. He called me a monkey during Madrid-Barca, 2. I did not shake his hand, 3. He spat on me, and after I threw the bottle, sorry for my attitude".
Speaking to RF1 later on Wednesday, the 34-year-old Mali international explained he had decided before the game not to shake the Portugal international's hand and was provoked into throwing the bottle when Pepe spat at him.
"At the time I played with Barcelona, Pepe called me a 'macaco', that is to say a monkey, and he spat on me. I told myself: 'This guy is worthless,'" he said.
"At the time, I did not speak publicly about it because it wasn't worth it. That's why I didn't shake his hand before the friendly. I even told my intention to my team-mate Mehdi Benatia. So I greeted everyone except him.
"And suddenly he came up behind me and spat on me. At the time, I had a bottle of water and I threw it at him. His team-mates saw us and they had the intention to strike me.
"It's true that I gave a bad image of myself and I apologise. But it's lucky we were on a football field because it's unacceptable that one man spits on another. I don't see why I would shake his hand, because in his eyes I'm not a human being.
"I don't want to talk to someone who does not consider me a human. His behaviour is unacceptable. Instead of asking why I didn't shake his hand, he preferred to spit on me.
"I'm not saying I'm a saint. Like everyone I have flaws, but I respect people."
Keita's comments come during a week in which racism has once more grabbed the headlines in Italian football, with Fifa demanding an investigation after FIGC vice-president Carlo Tavecchio referred to young African players moving to Serie A as "banana eaters".
Keita, however, does not believe racism is endemic in European football.
"No, we shouldn't generalise," he said. "I am African and I've played a long time in Europe. I have often met wonderful people.
"From time to time there are small-thinking ones who are not very nice, but I've rarely had to endure such behaviour. For me, that is too many. If some use football to say and do anything, it's a minority. I don't want to generalise."