Emile Hirsch -- I Got No Beef With Jim Belushi ... After Movie Role Diss

Emile Hirsch won't let a little thing like nepotism bring him down ... telling us he's all good with Jim Belushi after the actor said his own son would play a better John Belushi than Emile in the upcoming biopic.

Emile already locked up the role and production is set to begin very soon ... but when we asked Jim about the casting choice this past weekend, he told us he wanted to keep it in the family.

So, how did Hirsch deal with Jim's comments -- he's actually cool with it ... or at least that's the way it seemed as the actor left Fig & Olive restaurant in L.A. last night.

Fun Fact: Fan boys FREAKED OUT when Batman producers announced Heath Ledger would play the Joker in "The Dark Knight" ... and he turned out to be awesome (Oscar, hello?!).