Guardiola, the new Bayern Munich manager, left the Nou Camp last summer after winning 14 trophies in four seasons with the Catalan giants.
His assistant Tito Vilanova would add another Primera Division title to the cabinet this year but missed much of the spring campaign following a cancer diagnosis.
The Bayern boss last week spoke of a rift between himself and Rosell in Spanish newspaper Marca, suggesting the club's president had claimed he failed to visit Vilanova while the latter was receiving cancer treatment in New York, where Guardiola was spending a year on sabbatical.
Quoted on Marca.com, Rosell told 8tv: "We're very surprised by his statement. You can verify what we've said about the best manager in the history of the club in the newspaper archives.
"His words surprised me because when you're accused of something there should be some proof. We would never use Tito's illness and that's why I don't understand."
Guardiola was also quoted as saying the Barcelona board had failed to leave him "in peace even from 6,000 kilometres away".
Rosell responded: "I have no idea what Guardiola was referring to when he said we must leave him in peace.
"From the day he left the Nou Camp until this weekend, when I congratulated him on his signing (of Thiago Alcantara) at Bayern, we hadn't spoken.
"This uproar is not good for Barca, but this should not taint his extraordinary career at the club, in which he won so many titles with the homegrown players."