The producers have been quick to dismiss the casting decision as coincidental, claiming the media "went nuts" over a "vague" similarity.
"I was sure everyone would only be talking about Jesus, but they were talking about Satan instead," said Downey in a statement.
"For our movie, Son of God, I wanted all the focus to be on Jesus. I want his name to be on the lips of everyone who sees this movie, so we cast Satan out."
Back in March, when the Obama resemblance was first discussed, the producers said: "The actor who played Satan, Mehdi Ouzanni, has previously played parts in several Biblical epics - including satanic characters - long before Barack Obama was elected as our president.
"We have nothing but respect and love for our president, who is a fellow Christian. False statements such as these are just designed as a foolish distraction to try and discredit the beauty of the story of The Bible."
The original 10-hour run of The Bible aired in the US in March 2013, attracting 13.1 million viewers for its premiere. 20th Century Fox releases the Son of God movie on February 28.
- Independent