A statement from the embassy said the Afghan citizens were hanged in Karj and Esfahan prisons, but the date of the executions was not reported.
The embassy said seven of the victims were residents of western Herat province, three of Takhar province, one from Laghman province and one from western Nimroz province.
The Afghan government has requested Iran halt or suspend the execution of Afghans, Khaama Press reported.
Iranian officials said Afghan and Iranian citizens face the death penalty or life in prison for drug smuggling convictions.
The Afghan embassy said at least 5,000 Afghans are imprisoned in Iran, most for drug smuggling charges.