The Rossoneri sold the Brazilian playmaker to Real Madrid in the summer of 2009 for a then world record fee.
Milan reluctantly agreed to part with the Samba star after benefitting from his considerable talent for six memorable years.
Kaka has struggled to produce his best since leaving Italy, with injuries and a loss of form seeing a former World Player of the Year reduced to a supporting role at the Bernabeu.
Real are prepared to let him leave and find regular games elsewhere, but their asking price and the sizeable salary involved are making transfer negotiations difficult.
Milan have found that out the hard way and Galliani says they are ready to turn their attention elsewhere.
"We were waiting on the opinion of a well-known Spanish economics expert, and that's now arrived," he told the Milan Channel.
"The operation is closed because there are too many risks."