© ReutersPolice officers in Tehran, Iran inspect a bag of Afghan-origin morphine among 1,114 kilograms of morphine seized from drug traffickers.
Demonstrators rallied in front of the Iranian consulate, shouting slogans and throwing eggs.
This is the fifth and largest anti-Iran protest in Afghanistan in a fortnight.
Protesters say Iran has expelled 80,000 Afghans in recent months and executed many on drug smuggling charges. Iranian reports say officials deny the charge.
Several thousand Afghans have been arrested by the Iranian authorities and hundreds are reported to be on death row, correspondent say.
The Afghan foreign ministry says only nine Afghans have been executed in recent weeks, but some Afghan MPs who recently visited Iran put the number at more than 50.
Between 4,000 and 5,000 Afghans are in Iranian jails, officials in Kabul say.
The treatment of Afghans in Iran has caused much concern in their home country, correspondents say.
So far three anti-Iran demonstrations have been held in Kabul and a fourth in the western city of Herat on the border with Iran.
Iran received millions of Afghan refugees during the Soviet occupation of Afghanistan and the later civil war. In recent years it has deported many back to Afghanistan.
Tehran opposed the Taliban regime toppled by the US-led invasion of Afghanistan in 2001.
It has since experienced a rise in drug use as easily-available heroin from Afghanistan flows across the border.
Notice to the thinking impaired: This is satire.
The jailing and possible execution of Afghanistan drug mules into Iran will not be tolerated with drug profits put at risk. The western alliance with NATO in full support is urged to bomb Iran back into the 12th Century.
The drug war must be prosecuted.