Hague, who embarks on his inaugural overseas trip in his new role just three days into the new coalition government, told the Times that "tackling nuclear proliferation [in] Iran" was a priority for the government.
"Iran's behaviour in recent years has been unacceptable to the great majority of the international community," he said.
Hague indicated that Britain would continue to push for United Nations sanctions, said the paper, as he prepared for talks with US Secretary of State Hillary Clinton.
The United States is in the process of enlisting support for a fourth round of sanctions against Iran at the UN Security Council, as Washington steps up efforts to halt the Islamic republic enriching uranium.
Administration officials have signalled "good progress" from not only Russia but also China, both veto-wielding council members.
Washington fears Iran is trying to develop atomic weapons, while Tehran insists its nuclear programme is peaceful.