No, iOS and Android does not support VSTs and frankly most mobile devices don't have the CPU power to perform the synthesis you are used to on a desktop. This is however changing rapidly we know.
FL Studio Mobile uses high quality sample based instruments made from Image-Line plugins and sample packs.
The latest FL Studio Mobile HD 2.4 iOS app (Android follows later) includes the MiniSynth (including 70 presets)
This MiniSynth is a real-time synthesizer ready to be used in your FL Studio Mobile projects.
Image-Line Support Team.