The Brazilian forward was one of the most sought-after players in world football before his summer move to the Spanish giants, with Chelsea, Manchester City and Real Madrid all reportedly interested in him.
"[Neymar] wanted to be play next to Messi and the rest of the team," Rosell told Cadena SER. "The key was that the player wanted to come to Barcelona.
"It was not about knowing how to negotiate. I spoke with his father when we met in Miami and we closed the deal there. Neymar's a very humble, friendly guy, a great teammate and a great player.
"He is not selfish on the ball, which is just what we want in a football player. Has has settled perfectly into the squad. Everything was based on that despite him having offers from Manchester City, Chelsea, Bayern Munich and Real Madrid."
Barca are currently top of La Liga, having won all eight of their games this season.