As an American I've long supported assisting rebels
The best way to support Iranians would be to mass-protest against the US-imposed economic sanctions demolishing their economy. US economic sanctions murder half a million people yearly, per latest medical studies.
Iran has been under extreme sanctions for 45 years. Trump has intensified them prior to military invasion, yes, but the entire US government apparatus is complicit in the murder of hundreds of thousands if not millions of Iranians through economic deprivation.