Iran's supreme leader Ayatollah Ali Khamenei said on Saturday the Islamic republic is ready to reciprocate if US President Barack Obama changes American attitude towards his country. "If you change your attitude, we will change our attitude," Khamenei said in a groundbreaking address to thousands of Iranians in the northeastern holy city of Mashhad which was broadcast on state television. Speaking a day after Obama offered Tehran a "new beginning" to turn back the tide on decades of mutual animosity, Khamenei -- the final decision maker on Iranian strategic issues -- said however Iran is yet to see any change in Washington's attitude towards Tehran. "We have no experience with the new American government and the new American president. We will observe them and we will judge," he said.