Speaking after returning from a visit to Tehran, Straw said Iran's new president wanted to bring the country in from the cold and have a normal relationship with the West. Straw added he was optimistic but the West must not push Tehran too far.
Straw said he hoped a lasting deal could be reached and achieving this would boost the moderate forces in Iran.
The parliamentary delegation had 15 meetings with administration officials.
"President Rouhani and his colleagues want a proper and normal relationship not only with the West but the rest of the world, and they want Iran to come in from the cold," said Straw.
He said the international community, including the UK, had often had a malign influence on Iranian affairs since the 1950s and must now do everything it could to help to support the president and not to give succor to hardliners.
MNA
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