http://www.seatrade-maritime.com/news/middle-east-africa/shipping-companies-stop-iran-business-as-us-indicates-secondary-sanctions-are-in-effect.html

The US has indicated that new business activity with Iran after 8 May within the wind-down period could be result penalties under secondary sanctions, and a number of major shipping companies including MSC and Maersk Tankers have stopped taking new Iran business. With the US withdrawing from the Joint Comprehensive Plan of Action (JPCOA) on Iran on 8 May there are two wind-down periods for existing business – after 90 days on 6 August and after 180 days depending on the type of business. With the US planning to apply secondary sanctions to non-persons involved in business with Iran, had been uncertainty about new business by non-US companies contracted after 8 May but completed before the end of the wind-down period – such as spot shipping related contracts.