Both clubs face a battle to finish in the European places this season after calamitous campaigns in Serie A, sitting well off the pace of the league's European spots.
"It is a pity not only for the club but also for the Italian and European football," Rummenigge told Gazzetta dello Sport.
"Teams like Milan and Inter are big names that are associated with the competition, but complaining [about not being there] does not help, something in the last five years has gone wrong.
"You have to have a clear plan with all the financial options available, but without going against the financial fair play.
"If you have a hole, you can't plug it without fresh money. I've read that Milan could be sold, but the new owner couldn't put too much capital in without going against the UEFA limitations.
"So it's up to us as big names find a solution to not penalise them more. There are clear, rigid laws but we must think about not hurting clubs too."
