So, say you're an international leader with brains, courage, and morals (at least relative to others designated as leaders in the main). What would you propose the rest of the world should do in the face of Trump's unwarranted, counter-productive sanctions against Iran?
First, you'd make clear that disagreeing with Trump is not stating support for Islamic theocracy over Iran. You are for secular democracy taking peaceful root in Iran. You denounce the coup orchestrated by the US CIA in 1953 against Iran.
Second, you state that every firm that will remain doing business with Iran or start doing business with Iran will receive tax breaks for as long as the Trump sanctions remain. You combine those tax breaks with sanctions against US commerce in general matching in a proportional way sanctions against firms doing business with Iran.
In other words, you block trade with the US in general in a way that hurts US international trade just as much as US sanctions hurt those doing business with Iran. Trade with Iran is smaller than trade with the US, but there is a ratio that should be applied in the aggregate.
You explain to the world that Trump will continue winning until the rest of the world stops him. Support him where he's right. Counter him where he's wrong. He's wrong on Iran vastly more than he's right.
Trump is counting on cowards and small thinkers dominating the rest of the world.
Finally, this is, admittedly, not a Christian proposal. That's why I referred to relative morals. Would I rather Christian principles hold sway? Of course. Read the Gospels and do.