No militant group immediately claimed responsibility.
A suicide vehicle bomber has attacked a police headquarters in the Iranian port city of Chabahar, killing at least three people and wounding several others, according to state TV. Reuters could not verify their authenticity.
"We express our condolences to the government and the people of Iran and the families of the victims of this attack", the Ministry of External Affairs said.
Earlier in the day, a vehicle laden with explosives went off close to a police headquarters in Chabahar, situated in the southeastern province of Sistan-and-Baluchestan.
In June previous year, IS militants attacked parliament and the shrine of Ayatollah Ruhollah Khomeini, the leader of the 1979 Islamic Revolution, killing at least 18 people and wounding more than 50.
An Iranian ethnic Arab separatist Sunni militant group and Islamic State both claimed responsibility for that attack.
In 2010, two suicide bombers killed at least 28 people, including some of the elite Revolutionary Guards, at a Shi'ite mosque in southeast Iran, an attack Iranian leaders said was backed by the United States.
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Iran´s Foreign Minister Mohammad Javad Zarif says "such crimes won´t go unpunished".
"Foreign-backed terrorists kill & wound innocents in Chabahar".
Such acts of violence will also "boost the Islamic Republic of Iran's resolve to fight terrorism", said Jahangiri, calling for all-out efforts to identify the perpetrators and bring them to justice.
Chabahar, near Iran's border with Pakistan on the Sea of Oman, is home to a new port recently built and is an economic free zone for the country.
He was apparently referring to a highly successful operation by Iranian intelligence services, which led to the capture in 2010 of Abdolmalek Rigi, the ringleader of the so-called Jundullah terror group.
India has said it is ready to invest up to $500m in the development of the port that is key to its ambitions to chart a route to landlocked Central Asian countries and Afghanistan, bypassing Pakistan.
"India strongly condemns today's despicable terrorist attack in Chabahar, Iran".