The Rossoneri are open to allowing the Portuguese attacker to leave the San Siro this summer as it would create space for incomings.
Leao has been linked with Everton, potentially in a swap deal for James Rodriguez, as super agent Jorge Mendes looks to wheel and deal in the transfer market.
However, Leao is not sold on the idea of joining Everton, according to Italian outlet Calciomercato.com, but is intrigued by the possibility of a switch to Dortmund.
The German side have shown interest in Leao, but have yet to go beyond a simple enquiry for the player.
It is claimed that if Dortmund were to firm up their interest in the forward then a deal to take him to Germany could take shape quickly.
AC Milan would be looking for at least €30m from the Bundesliga club.
Dortmund are set for a cash injection due to the big-money sale of Jadon Sancho to Manchester United.
