The 27-nation bloc, which frequently issues such condemnations on the eve of meetings with Iranian officials, voiced concern over reports that 10 Iranians were publicly executed last week alone.
It also signalled concerns about a parliamentary bill which it said would extend the range of offences carrying the death penalty to include the creation of websites deemed to disturb the "psychological security of society".
"The bill makes a disproportionate link between the acts committed and the penalty imposed and sets out to brutally restrict the exercise of freedom of expression," the EU said in a statement.
"The Iranian authorities have doubled the number of executions from 2006 to 2007, without achieving anything but a worsening crime rate," it said, urging an immediate halt on executions and a moratorium on the death penalty.
EU foreign policy chief Javier Solana is due to meet chief Iranian nuclear negotiator Saeed Jalili in Geneva on Saturday for talks aimed at clarifying Iran's reply to an international offer of trade, technical and other incentives if it suspends uranium enrichment.
Solana will be accompanied by officials from six major powers — United States, Russia, China, France, Britain and Germany. In a significant policy shift, Washington will be sending a senior envoy for the first time.
Iran rejects suspicions it wants the atom bomb. While Iranian officials have ruled out any suspension of enrichment before the meeting, European diplomats believe they have seen signs from Tehran that it is keen to resolve the stand-off.
(Reporting by Mark John, editing by Paul Taylor and Mariam Karouny)
