A suicide vehicle bomb targeted a bus carrying members of the Guards, the Guards said in a statement on Wednesday.
"Our response in defence of the Islamic Revolution will not be limited to our borders", Ali Fadavi was quoted as saying by Fars.
And in October, Jaish al-Adl kidnapped at least 10 security personnel, including several Revolutionary Guards, at a border post in Mirjaveh. Riyadh has denied the charges.
"We are not waiting until there becomes a battle in Saudi Arabia, so we will work so that it becomes a battle for them in Iran and not in Saudi Arabia", he said then.
FILE - A group of Iranian border guards march at the eastern border of Iran shared with Pakistan and Afghanistan, near Zabol, Sistan-Baluchistan Province, Iran, July 19, 2011. Thirteen people were wounded.
The attack happened on the road in-between the cities of Zahedan and Khash, a volatile area near the Pakistan border where militant groups and drug smugglers frequently operate.
The explosion was so powerful that the bus was turned into a twisted pile of metal. Reuters could not independently verify the image.
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The bombing was swiftly claimed by Jaish al-Adl, or the Army of Justice, which is linked to al-Qaeda.
Iran's Revolutionary Guard exert significant economic and military power within the country, answerable only to Ayatollah Ali Khamenei, the supreme leader. Recent militant assaults inside Iran have sparked retaliatory ballistic missile strikes in Iraq and Syria. It runs a business empire in Iran worth billions of dollars.
Also, Iran's Foreign Ministry Spokesman Bahram Qassemi condemned the attack and said the victims will soon be avenged.
The attack comes two days after Iran marked the 40th anniversary of its 1979 Islamic Revolution.
Iranian Revolutionary Guards corps is a US designated terror organization.
Dubbing the meeting in Poland the "WarsawCircus", Iranian Foreign Minister Mohammad Javad Zarif said it was "no coincidence that Iran is hit by terror on the very day" that the talks began in the Polish capital. In 2009, more than 40 people, including six Guard commanders, were killed in a suicide attack by extremists in Sistan and Baluchistan province.
Militants disguised as soldiers opened fire on the annual Iranian military parade in an attack claimed by the Islamic State terrorist group.