Japan does not agree with sanction as a tool of pressure against Iran, Japan's ambassador to Tehran Kinichi Kumano said, ISNA reported.
"Although the US unilateral sanctions had left adverse affects on activities of Japanese firms in Iran, but Iran-Japan trade cooperation stands in a good level," he told.
He said Tehran-Tokyo financial cooperation hit over $13,0,000,000 in 2010 and 110,000,000 of which included energy exports to Japan.
He reiterated many Japanese firms are working both with the US and Iran.
The ambassador also expressed hope that new round of talks between Iran and the five permanent members of the UN Security Council plus Germany would bear fruitful results.
Tehran has been under four rounds of the UN Security Council sanctions over its refusal to halt peaceful uranium enrichment.
The West accuses Iran of making nuclear weapons. Tehran denies the allegation saying that its nuclear work only aims to meet domestic needs including power generation and medical needs.
Iranian top nuclear negotiator Saeed Jalili had already answered Ashton's letter, saying the country would welcome P5+1 return to talks.
Iranian Supreme National Security Council Secretary Saeed Jalili in a letter to the European Union Foreign Policy Chief Catherine Ashton had welcomed P5+1 return to the table of negotiations.