The project, which will transpose Conan Doyle's detective to present-day New York, has been compared to Moffat's BBC drama Sherlock.
"They approached us to remake our show, we said no and they just decided to make one anyway," Moffat told journalists at a press conference this morning (March 21).
He added: "I'll just leave you to speculate on what I think about that!"
However, Moffat reiterated that Elementary is not officially considered a remake of Sherlock.
"That's not a re-version of our show, they just decided to make one anyway," he said.
The writer - who also works on Doctor Who - also joked that a US remake of the sci-fi drama would be "blasphemy".
"It wouldn't be up to me, because the BBC owns Doctor Who and not me, but I don't think it would be a good idea," he explained.
"There's only one Doctor and Doctor Who is a hit over there already, so no, I wouldn't like that personally."
Elementary is currently under consideration for the CBS 2012-13 television season. A third series of Sherlock is expected to start filming in 2013.
> Sherlock Steven Moffat: 'We haven't started writing new series yet'
Watch a clip from Sherlock's 'The Reichenbach Fall' below: