The Brazilian club have admitted that they are willing to let the 24-year-old full-back leave for a certain price and claim the deal is making progress
The former Sevilla full-back has another year on his contract but has been heavily linked with a move away from Camp Nou throughout the summer.
Recent reports in Spain have linked them with Douglas, 24, and the Brazilian club say the deal is in progress to take the player to Catalunya.
"Barca want to sell Dani Alves and are looking for a replacement for him, who would be Douglas," Aidar is quoted as saying by Sport.
"The sale isn't completed because we still have to talk and the economics involved in the operation are the Traffic group [who own 40 per cent of Douglas' rights], Juan Figger [an intermediary], Sao Paolo and Barca.
"Two months ago our partner Figger asked if we would sell the player to Barca. We said we were willing to negotiate.
"He's doing everything and things are progressing well. We haven't spoken directly to Barca but we are aware of their interest, so are the agents, Traffic. I guess they have already spoken to the player."
Dani Alves was linked with a switch to Paris Saint-Germain earlier this summer but the French champions opted to sign Serge Aurier on a loan deal.