The actor made the comments during a Q&A with the audience following a screening of 'Oppenheimer' at the Aero Theater in Los Angeles.

"I'm pretty sure that I heard like, 'There's this role, Scarecrow,' and I was like, 'psh, I'm Scarecrow'," Downey Jr. said in a video shared on X by Griffin Schiller.

He continued: "I remember meeting for tea, and I was like, 'He doesn't seem like he's really leaning in on this interview.' And he was polite and all that, but I mean, you know, you can tell when someone is kind of like, 'It's not gonna go your way'."

The role of Dr. Jonathan Crane, the Scarecrow, would ultimately go to Downey Jr.'s Oppenheimer co-star Cillian Murphy, reports deadline.com.

Nolan recently recalled why he cast Murphy as the villain instead of the titular character in Batman Begins.

In an interview with EW, Nolan said he had been reading about Murphy starring in 28 Days Later but after a screen test the actor said he didn't feel like “Batman material."

"We did two scenes --there was a Bruce Wayne scene and a Batman scene -- and I made sure that executives came down and watched what you were doing on set," Nolan recalled.

"Everybody was so excited by watching you perform that when I then said to them, ‘Okay, Christian Bale is Batman, but what about Cillian to play Scarecrow?' there was no dissent."

Nolan continued: "All the previous Batman villains had been played by huge movie stars: Jack Nicholson, Arnold Schwarzenegger, Jim Carrey, that kind of thing."

"That was a big leap for them and it really was purely on the basis of that test. So that's how you got to play Scarecrow."