The new restrictions are part of a "twin-track approach" to both negotiate and continue pressure on Iran, French Foreign Minister Laurent Fabius said in a Wall Street Journal report.
EU foreign ministers approved the sanctions at a meeting in Luxembourg.
One new measure bans all financial transactions between European and Iranian banks. Another imposes more restrictions on Iran's central bank.
Also, export of materials that can be used for industrial or military purposes will be prohibited, and rules are designed to impede Iran's shipbuilding capabilities and the movement of its tankers and cargoes.
"Talks with Iran have until now not led to enough substantial progress so we have to step up sanctions," German Foreign Minister Guido Westerwelle said.
"The United States welcomes the adoption by the European Union of significant new sanctions of the Iranian government in response to the Iranian government's continued violation of its international obligations regarding its nuclear program," Carney said in a statement.
"As you know, rallying the world to isolate Iran and increase the pressure on its leadership so that they stop pursuing a nuclear weapon has been a top priority for the president since the day he [Obama] took office," Carney said.
The EU also hit Syria with another round of sanctions, the 19th since the country's continuing conflict began last year.
Additional restrictions were added to the import of arms into Syria, and transport of weapons to Syria from EU countries was banned.
Two more firms and another 28 individuals were added to a list banned assets and travel prohibitions. The list now totals 181 people and 54 companies involved in the fighting against Syrian rebels.
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