Every US company/citizen is not allowed to do trade with Iran due to the ITSR laws except under highly specific situations.

It gets more complex if a company is multinational though.

A citizen can travel to Iran but even if they buy something there on holiday if they bring it back to the US they need to go through complex customs procedures to make sure its legally brought back in.

It's a US-sanctioned country so allied nations play along with the sanctions and Binance is located within that US sphere of influence so Iran is supposed to be currently banned, yes.