Re: Iranian sanctions?
Not at all.
There are 10+ sanctions acts on the USA statute book against Iran. So USA lifting the nuclear part of the sanctions means totally bugger all as far as doing business with Iran. You can still fall under the sanctions (this is just off the top of my head) regime on: missile development, the bombing of Buenos Aires Jewish center of 1994, Hezbollah support and god knows what else. This is even if we do no count the Iranian Nuclear Program Congress anti-Obama Sour Grapes Act of 2015 (aka H.R.158 - Visa Waiver Program Improvement and Terrorist Travel Prevention Act).
So from the perspective of doing business with Iran - you still have a choice of doing business with Iran or doing business in/with USA. This is one of the reasons why no EEA major bank has announced full lifting of restrictions on financial operations with Iran. They are still being operated in "special checks" mode (if at all).
In the specific case of ZTE and Co this also is specifically aligned to internal US telecoms politics. Part of it is bog standard anti-competitive, the other part is the rabid paranoia shaking the US 3 letters after they went to the Chinese vendors for the same special feature sets as used in the Snowdenian revelations and got an immediate quote and availability back.