Iran has summoned ambassadors of the United Kingdom, Netherlands and Denmark, accusing them of harbouring Iranian opposition groups, Iran's Islamic Republic News Agency reported.
The Saudi-linked Patriotic Arab Democratic Movement in Ahwaz has reportedly claimed responsibility for the attack.
"It is not acceptable that these groups are not listed as terrorist organizations by the European Union as long as they have not carried out a terrorist attack in Europe," Iran's Islamic Republic News Agency quoted Iranian foreign ministry spokesman Bahram Qasemi as saying.
Previously, Iranian Armed Forces spokesman, Brig. Gen. Abolfazl Shekarchi said that the militants who had committed the terrorist attack were linked to the United States and Israel. Iranian Foreign Minister Javad Zarif had also accused "regional terror sponsors and their US masters" of organizing the attack.