The EU is set to reveal new sanctions on Iranians for human rights abuses, the first such measures since 2013, diplomats said.
The bloc's envoys are expected to agree on travel bans and asset freezes on Wednesday.
The names of those who face sanctions will be published next week, when the measures take effect. The EU declined to comment.
The bloc has issued sanctions over human rights abuse on more than 80 Iranians since 2011. These are renewed annually every April.
Existing sanctions will also be renewed on Wednesday, the diplomats said.
One said the EU wanted to take a tougher stance to uphold human rights.
This month, it placed sanctions on 11 people from countries including China, North Korea, Libya and Russia.
"Those responsible for serious rights violations must know there are consequences," an EU diplomat said.
The UN has regularly complained that Iran arrests political opponents to stop freedom of expression.
On March 9, UN special rapporteur on human rights in Iran, Javaid Rehman, presented a report documenting Tehran's high death-penalty rate and execution of juveniles.
The report also told of torture to coerce people into making confessions and the legal marriage of girls as young as 10.
Iran has repeatedly rejected accusations by the West of human rights abuses.
But no Iranians have been added to the EU's sanctions list since 2013, as the bloc shied away from angering Tehran in the hope of protecting a nuclear accord Iran signed with world powers in 2015.
The diplomats said the sanctions were not linked to attempts to revive the nuclear deal, from which the US pulled out but now seeks to rejoin.
The deal limited Iran's nuclear programme in return for sanctions relief.
"Tehran has grown increasingly exasperated with Europe, especially in the past several months, as the nuclear issue remains stuck," said Eurasia Group analyst Henry Rome.
"And the new sanctions will probably further fuel frustrations that Europe is simply falling in behind Washington.
"For its part, Europe has a very delicate balancing act.
"It is trying to demonstrate that its desire to revive the nuclear agreement will not come at the expense of human rights, while also trying to ensure that its support of human rights does not come at the expense of the nuclear agreement."
The EU revoked its broader set of economic and financial sanctions on Iran in 2016 after the nuclear deal was struck.
But it did impose sanctions on an Iranian intelligence unit and two of its staff in 2019, claiming Tehran plotted attacks in Denmark, France and the Netherlands.
In a rare move last September, France, Britain and Germany summoned Iran's envoys to admonish them about what the French Foreign Ministry said were "serious and constant violations" of human rights.
In March 2018, the three countries pushed for sanctions over Iran's missile programme and its involvement in Syria.
But other EU governments feared it could also upset European companies' chances of winning lucrative contracts in Iran as it tried to open up after decades of isolation.
