The sanctions include an asset freeze against 82 individuals and one entity, plus a ban on exports to Iran of equipment "which might be used for internal repression and of equipment for monitoring telecommunications".
The names will be published tomorrow in the EU's Official Journal, a statement said.
The European Council of member states said it decided to extend the sanctions in response "to serious human rights violations in Iran".
The measures were first put in place in 2011 following a crackdown during the 2009 election and subsequent protests sparked by the Arab Spring which inspired hopes of reform.
The EU and other top world powers reached agreement with Iran in 2015 on curbing its nuclear programme and they began easing economic sanctions in January 2016.
Brussels billed the agreement as clearing the way towards improved relations with Iran but progress has been slow and tensions have risen over Tehran's continued support for Assad who the EU believes must step down if there is to be peace in Syria.