The actor, who reprises his role as Tony Stark in the series' third instalment, injured his ankle performing a stunt on set.
Marvel released a statement as follows: "Robert Downey Jr sustained an ankle injury on the set of Iron Man 3 in Wilmington, North Carolina while performing a stunt. There will be a short delay in the production schedule while he recuperates."
Gwyneth Paltrow and Don Cheadle return to play Pepper Potts and James Rhodes respectively, and it has been rumoured that Paltrow's character may wear her own Iron Man suit at some stage in the film.
True Blood actress Dale Dickey has been added to Iron Man 3's cast, while other new additions include Guy Pearce, Ben Kingsley, Rebecca Hall and James Badge Dale.
> 'Iron Man 3' releases first Tony Stark concept art
> Robert Downey Jr: 'I don't know where you go after Iron Man 3'
Iron Man 3, which is directed by Kiss Kiss Bang Bang helmer Shane Black, will be released on April 26, 2013 in the UK and May 3, 2013 in the US.
Watch a trailer for Iron Man 2 below: