Barcelona sporting director Albert Soler has confirmed the club are in a "legal process" over Gabriel Barbosa's transfer from Santos to Inter.
Brazil international Gabriel signed a five-year deal with the Serie A club at the end of last month, having been courted by a number of Europe's major clubs.
Barca signed Neymar from Santos in 2013 and reportedly paid the Brazilian club to have a preferential option on Gabriel and his team-mates Victor Andrade and Giva at that time.
Tuttosport reported this agreement meant the LaLiga champions would have to be informed of any bids made for the players and given three days to respond.
Barcelona resident Josep Maria Bartomeu told RAC this week that Santos did not respect the terms of the agreement and pledged to "defend our interests".
Speaking at an introductory news conference for Spain forward Paco Alcacer, Soler said Barca would follow through on this.
"The club is in the legal process," he said. "We had an option of first refusal that was not fulfilled by Santos.
"We are studying all legal possibilities to follow the case, but this is not a [news conference about] legal and sports management."
Alcacer arrived at Camp Nou from Valencia, ending a lengthy pursuit for forward reinforcement in Luis Enrique's squad.
A number of prospective signings were put off by the prospect of Lionel Messi, Luis Suarez and Neymar restricting their game time but Alcacer is relishing the challenge.
"I come to the best club in the world. For me it is a very nice experience," he said. "I will learn a lot, both in sports and personally.
"When this club is interested, it is hard to say 'no'. Coming here takes you to another sporting level and I think it will be very good for me.
"I'll play where the coach says. My position is number nine, but if I have to play for the team, I will. I have no problems.
"Signing for Barca is a step forward in my career. I will do my best to make it difficult for the coach. I know I have to make the most of the opportunities that I have."