US President Barack Obama renewed his administration's offer of dialogue and diplomacy with Tehran Saturday, a year after his offer of a new beginning with Iran failed to achieve concrete results. Obama, who addressed Iranians in a new videotaped appeal to mark the Iranian new year has pledged to pursue aggressive sanctions to prevent Iran from getting a nuclear weapon. “We are working with the international community to hold the Iranian government accountable because they refuse to live up to their international obligations,” Obama said in the address, according to excerpts released by the White House. “But our offer of comprehensive diplomatic contacts and dialogue stands,” he said. Obama said Washington was committed to a “more hopeful” future for the Iranian people despite US differences with Iran's government. During his first year in office, Obama marked Iranian new year with a then-unprecedented message offering Iran a “new beginning” of diplomatic engagement with the United States. But Tehran rebuffed Obama's gesture and relations soured further when Iranian authorities cracked down on opposition protesters after a disputed election last June, drawing US condemnation. “Over the course of the last year, it is the Iranian government that has chosen to isolate itself, and to choose a self-defeating focus on the past over a commitment to build a better future,” Obama said. “Even as we continue to have differences with the Iranian government, we will sustain our commitment to a more hopeful future for the Iranian people,” he said. Obama said the United States was increasing opportunities for educational exchanges for Iranian students to study at US colleges and universities as well as working to increase access to Internet technology so Iranians could “communicate with each other, and with the world, without fear of censorship.” Obama's openness to engaging diplomatically with Iran if it “unclenched its fist” broke with the previous administration's policy of seeking to isolate Tehran, which former US president George W. Bush branded part of an “axis of evil.” Obama has not ruled out any options in dealing with Iran but US officials have repeatedly made clear that their preferred option is diplomacy, given the difficulty of enforcing sanctions and the risk that military action could cause wider conflict. State radio in Iran quickly accused the Americans of “pursuing the same Iranophobic policy” as always.