Gaspart was hitting back at claims that Barca have tried to bribe Granada players and officials ahead of their crucial La Liga clash on Sunday.
Barca travel to Granada on the final day of the season leading rivals Madrid in the standings by one point, meaning a win will confirm back-to-back titles for the Catalans.
Gaspart was furious with the claims and insisted Granada players should be offended that such suggestions would even be made.
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"The only thing Real Madrid do is harm football," the 71-year-old told Spanish newspaper Ara.
"If I was a Granada player I'd be offended, because it insinuates that I could be bought, it's an indecent campaign.
"I believe in football and its honesty. If such things are discovered, though - through secure investigations - then the clubs involved will have to be punished."
Gaspart - who is vice president of the Royal Spanish Football Federation - was also asked about a scandal in the 1990s involving Barca and Madrid.
Barca are alleged to have paid Tenerife €7 million after they beat Madrid on the final day of the season to hand the club the title two seasons in a row.
"Whoever says that is a liar," he exclaimed.
"All Barcelona did was invite Tenerife to [pre-season tournament] the Gamper, not a euro was paid."