metallic click sound when starting off forward or reverse

On my 2004 grand caravan when starting off I hear a metallic click sound from the front left. It occurs one or twice then I don't hear it was I am underway. This is not like the clunk you hear from bad sway bar bushings. This occurs only when starting off from a stopped position. At least that is only when I hear it.

Someone suggested it was a rotor/pad issue, but I don't why that would be the case.

Any suggestions?

Thanks.