The package of "sanctions against Iran has been adopted" at a meeting in Brussels, the diplomat said. Most of the sanctions will take effect on Tuesday when they are published in the EU's official journal.
The new EU sanctions include a ban on the sale of equipment, technology and services to Iran's energy sector, hitting activities in refining, liquefied natural gas, exploration and production, diplomats said.
There is also a ban on new investments in the energy sector.
The EU is also banning dual-use goods that can be used for conventional weapons. It will also step up vigilance of the activities of Iranian-connected banks operating in the EU and bar them from setting up branches.