Dozens of suspects have so far been arrested in the ongoing investigations into the attacks that killed 17 people on Wednesday - the first assault in Iran to be claimed by the Islamic State militant group. Then, on June 6, Saudi Foreign Minister Adel al-Jubeir said Iran had to be "punished" for what he called "its interference in the region".
File image of Iran's foreign minister Javad Zarif. The attack was claimed by Islamic State militants via its news agency Amaq.
The terrorist acts included the assassination of high-profile Iranian officials as well as the killing of ordinary citizens, he said.
Zarif told the forum that recent Saudi officials' remarks against Iran are a "direct threat and very unsafe provocation".
Last week, the Revolutionary Guards linked the "brutal attack" to Donald Trump's visit last month to Riyadh, where the United States president pointed the finger at Iran for fuelling "the fires of sectarian conflict and terror".
Two large regional powers on either side of the Sunni-Shiite Islamic sectarian divide, Saudi Arabia and Iran have been engaged in a longstanding cold war, tussling for influence in countries in their sphere of influence, especially Syria, Lebanon and Yemen, where Saudi-led bombing has left thousands of civilians dead.
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The fighting has devastated communities in both countries and forced hundreds of thousands of people to flee their homes. He said women and children were among the dead, but he could not immediately give a specific number.
Saudi Arabia gained, boosted by banks, on expectations for a rate hike in the United States.
Iran's Revolutionary Guard quickly, but with deliberate vagueness, incriminated Saudi Arabia and the United States.
Following Iran's Islamic revolution in 1979, both countries discontinued diplomatic relations. Under the JCPOA, Iran undertook to put limitations on its nuclear program in exchange for the removal of nuclear-related sanctions imposed against Tehran. They could not even tolerate huge turnouts in Iranian elections and, as a result, began to carry out acts of terror, added the MP.
"In any case", Mogherini said, "the European Union will guarantee that the deal keeps, that we stick to that. and that our policy of engagement with Iran continues".
Zarif had arrived in Oslo on Monday to take part in Oslo Forum.
The meeting was held Tuesday on the sidelines of the Oslo Forum, 2017 June 13-14.