Iran's former ambassador to Australia Mohammad Roohi-sefat, in an interview, said Iranian foreign minister's recent visit to European country was a successful trip.
Speaking to ILNA news agency correspondent, he refers to zarif's visit to Japan and added "Tokyo wants to continue its cooperation with Tehran in various fields."
"Japan is Iran's second largest trading partner in recent years and also is one of our most important oil buyers."
Iranian ex-diplomat also said that the visit of Iran Foreign Minister to China is also very important; China has publicly announced that it will continue to buy oil from Iran.
Japan will try to help ease tension in the Middle East, Foreign Minister Taro Kono said on Tuesday as he began a meeting with his Iranian counterpart, Mohammad Javad Zarif.
Tension between Iran and the United States has risen since President Donald Trump's administration last year quit an international deal to curb Iran’s nuclear ambitions and began to ratchet up sanctions.
Iranian officials have denounced the new penalties as "economic warfare".
French President Emmanuel Macron opened an avenue towards a diplomatic solution to the U.S.-Iran standoff at a Group of Seven summit on the weekend, saying that Iranian President Hassan Rouhani had told him he was open to a meeting with Trump.
Trump told a news conference it was realistic to envisage a meeting with the Iranian head of government in coming weeks. Both leaders are scheduled to attend the U.N. General Assembly next month.
But on Tuesday, Rouhani said Iran would not talk to the United States until all sanctions were lifted.