The new sanctions, adopted by EU foreign ministers at a meeting in Brussels, target the Iranian financial and trade sectors as well as the energy industry. The package includes visa bans and asset freezes for Iranian banks, the Islamic Revolutionary Guard Corps and Iranian shipping companies.
EU foreign ministers called the measures "robust and comprehensive" and said they're aimed at ending the years-long conflict.
"The aim of the EU is to achieve a comprehensive and long-term settlement which would rebuild international confidence in the exclusively peaceful nature of Iran's nuclear program, while respecting Iran's legitimate rights to the peaceful uses of nuclear energy," they said in a statement issued Monday after the meeting.
The ministers urged the Iranian regime to "seize this opportunity to allay the concerns of the international community about its nuclear program and agree on a concrete date" for the resumption of negotiations.
Iran denies Western allegations that its nuclear program is aimed at building nuclear weapons, vowing instead that it is for civil and energy purposes only. So far, Western sanctions have failed to pressure Iran into halting nuclear enrichment and cooperating with the West. Tehran argues it has the right to pursue nuclear energy independent from international oversight.
The new EU measures come on top of a fourth round of sanctions imposed by the United Nations in June. For the first time, Europe targets the heart of Iran's economy: The oil and natural gas sector.
The second-largest producer of the Organization of Petroleum Exporting Countries, Iran has proven oil reserves of around 137 billion barrels, figures from OPEC indicate.
A significant share of Iran's state revenue is generated with oil and gas sales but the Iranian opposition says the clerical regime is cashing in the energy money to build up its security apparatus instead of improving the lives of ordinary Iranians.
Yet Iranian officials said the new measures would only heat up the conflict.
"Sanctions are not considered an effective tool ... and they will only complicate the situation," Ramin Mehmanparast, an Iranian foreign ministry spokesman, was quoted by state news agency IRNA as saying.
Meanwhile, Iranian Oil Minister Masoud Mirkazemi vowed that the sanctions wouldn't affect the Iranian energy sector.
"All our oil and gas fields are being developed by Iranian companies," Mirkazemi told IRNA. "European oil companies had no presence (in Iran's energy sector) and so they cannot have any impact on us."