The 30-year-old two-time world player of the year insisted that if it was up to him he would already be playing for his former club in the Brazilian league.
"I'm not up for auction. If it was up to me I'd already be wearing the Gremio jersey even if it means earning less," Ronaldinho told the Globoesporte website.
"The problem isn't the offer that has been made for me but Milan's demands."
Italian daily Gazzetta dello Sport reported Tuesday that the Brazilian had already signed for Gremio where he started his career in 1998.
The sports newspaper claimed Ronaldinho's brother and agent Roberto de Assis had reached an agreement with Gremio, and a meeting was planned Wednesday.
Premier League club Blackburn were also reported to be making a multi-million euro bid to bring the former Barcelona and Paris St Germain forward to England.