The 34-year-old agreed the mutual termination of his contract with Atletico Mineiro on Monday, bringing to an end his two-year stay at the club.
Rumours then surfaced that Ronaldinho could replace Juan Roman Riquelme as Boca's talisman following the former Villarreal star's exit from the club earlier in July.
However, the Argentine giants have moved swiftly to put an end to the speculation by declaring that they are only in the market for defenders.
A senior club source told Goal: "[Jose Pedro] Fuenzalida is the last reinforcement and we will only sign somebody for the defence in the event we sell another player."
An agent in Australia revealed on Tuesday that the A-League is a possible destination for Ronaldinho and expects several clubs to make a play for his services in the coming weeks, while QPR have been linked in England.