Bad blood boiled up between the Spanish giants around four clashes in three competitions in 18 days late last season and Rosell used his end-of-campaign news conference to read out a strongly-worded statement condemning Real.
"We believe that this season Real Madrid has gone beyond all the limits of the necessary sporting rivalry, making accusations against our club that have no foundation," Rosell said.
"The rivalry will continue next season but we will not allow the limits of sporting behaviour to be exceeded again.
"Football deserves clean competition and FC Barcelona will do everything to preserve that.
"If necessary, we will take legal action and take the case to the relevant sporting tribunals."
Real responded with a statement in which they said they regretted Rosell's "unfortunate comments."
The club said his statement was motivated by "pressure the board of directors has been placed under by part of a certain and nearby media environment, which has called for an aggressive attitude towards our club".
"For the good of football, Real Madrid CF will continue working to maintain the best possible relations with FC Barcelona, as it typically does with all clubs in Europe and the world," the statement added.
CHEATING, ABUSE
European champions Barca eliminated Real from the Champions League and beat the Madrid club into second place in La Liga for a third successive season. Real claimed a dramatic King's Cup final win over Barca to win their only silverware of the campaign.
The four matches were marred by play-acting, brawling and allegations of cheating and racist abuse.
After the Champions League semi-final first leg, Mourinho said Barca enjoyed favourable treatment from referees and Real later filed a complaint with UEFA - which was rejected - accusing Barca players of diving and alleging midfielder Sergio Busquets had called defender Marcelo a monkey.
Barca filed their own complaint with UEFA over Mourinho's comments and the Portuguese was suspended for five matches and fined 50,000 euros.
He faces an appeals hearing on July 29 and has said he will use every means at his disposal to fight the sanction.
"The news conference that the Real Madrid coach gave after the Champions League semi-final first leg at the Bernabeu shamed anyone who considers themselves an athlete," Rosell said.
Barca were also outraged by a report on Spanish radio station Cadena Cope, which cited an unidentified Real official as its source, that suggested Barca's players and medical staff were engaged in illegal doping.
"I can assure you that if someone, in the name of FC Barcelona, had made an accusation of this kind we would have acted with firmness, denying it immediately and taking those responsible to court," Rosell said.
"We would have appreciated a similar response from Real Madrid but unfortunately this was not the case."
