It seems Iran has turned down the offer but why Italy is helped only by China, Cuba and Russia, and not Germany or the USA?
At first, US is generally not going to help anybody despite itself:
So, if US is not going to help anybody, why do US offer its help? Just because it is obvious, that such offer would be rejected. Both Iran and NK are under high pressure from US sanctions. With Iran, US even have a proxy-war in the middle-east. And after all that US offers help? It looks like a diplomatic taunt, not a real, serious offer.