Hardline President Mahmoud Ahmadinejad on Thursday warned European countries not to follow the US lead in imposing unilateral sanctions against his country, state radio reported. Ahmadinejad threatened unspecified retaliation by Iran if Europe followed in the footsteps of the United States, which last week announced sanctions against the Islamic state. "If they plan to cooperate with the enemy of the Iranian nation, we cannot interpret this as a friendly behavior. We will show reaction," the radio quoted Ahmadinejad as saying. Meanwhile, US Undersecretary of State Nicholas Burns told reporters that Washington wants a third UN Security Council sanctions resolution passed as soon as possible. He also said the US wants the European Union to push forward with further sanctions against Iran, and urged Iran's major trading partners to cut back business with Teheran to send a strong message. "Our view is that all of that should happen as soon as possible so that Iran gets the message that as long as it's defying the Security Council, which it currently is, and not cooperating fully with the IAEA ... then there's going to be a price to what Iran does," he said. "And that price will be increased isolation and heightened sanctions." The US measure bans dealings with a host of companies connected to Iran's Revolutionary Guards, an elite force that has extensive business holdings in oil, construction and other sectors. It also prohibits American companies from working with the Guards-linked Iranian companies and puts pressure on international firms and banks not to deal with them as well. Ahmadinejad spoke after a ceremony inaugurating a petrochemical complex in the southern port of Asalouyeh, some 1,500 kilometers south of the capital, Teheran. "You, Europeans, know well what will happen in the economic sphere if Iran takes a serious move in this matter," the Iranian leader said. IRNA, the state official news agency, also quoted Ahmdinejad as saying: "You, Europe, need us more" - a veiled reference to business ties between Teheran and European nations. According to official statistics Europe is Iran's largest trading partner, with over 40 percent of Iran's imports coming from European Union countries. Also, many European energy companies have been working in Iran's attractive energy market, which is the second oil producer among OPEC countries. Ahmadinejad also spoke against a new, third round of UN sanctions, saying that "enemies of Iran should know that the era of unanimous (UN) resolutions against the Iranian nation has passed." Iran is counting on international support from Russia and China - permanent UN Security Council members - to prevent harsher UN sanctions. The UN has imposed two rounds of limited sanctions for Iran's refusal to suspend uranium enrichment, a process which can be used for both nuclear fuel for electricity power plant and weapon. Russia and China have resisted a third round of sanctions. IRNA said Ahmadinejad called sanctions against his country a "ridiculous story." Burns noted that Iran did not accept an offer last week from EU's Javier Solana to negotiate, saying Teheran had "chosen the route of sanctions." "We hope that Iran will reconsider, suspend its enrichment program and come to negotiations with the United States and with the other countries" on the Security Council, Burns said. "That offer is on the table but Iran continues to refuse it," he said. Burns, in Vienna for two days, is to meet Thursday with Mohamed ElBaradei, head of the International Atomic Energy Agency. Burns said it was important for the UN Security Council and the Vienna-based IAEA to be "tied together." "Dr. ElBaradei has made statements in the past that would seem to indicate that sanctions might not work or that enrichment is not going to be suspended and obviously as co-authors of Security Council resolutions, we take some issue with that," Burns said. "I think the real problem here is not Dr. ElBaradei or the United States - it's Iran," Burns said.