Iran will not give in to "bullying" at the negotiating table with world powers over its disputed nuclear programme despite new economic sanctions, its supreme leader said on Tuesday.

The West "keeps saying pressure against Iran is aimed at forcing the Islamic republic to return to the negotiating table" about the nuclear programme, Ayatollah Ali Khamenei said in remarks carried on state television.

"But when did we leave the table that now we need to return?" he asked during his visit to the northeastern province of North Khorasan.

"Their real objective is (forcing) the Iranian nation to surrender to their bullying at the negotiating table... (but) you are too weak to bring Iran to its knees," said Khamenei.

His remarks came a day after the European Union toughened sanctions against Tehran, targeting its dealings with Iran's banks, shipping and gas imports and banning trade in metals.

Without directly mentioning the sanctions, Khamenei accused the European leaders of seeking to bully Iran.

"European officials are still stuck in the bullying mindset of the colonial 19th century, but they will face many problems in the face of the resistance of the Iranian nation and officials," he said.

The measures announced on Monday add to a series of sanctions from Europe, the United States and the UN Security Council designed to pressure Iran to curb its nuclear programme.

Khamenei has termed the Western sanctions as "barbaric" and said they amount to "a war against a nation." But he has said Iran can overcome problems caused by the sanctions.

The West is involved in talks with Tehran on the nuclear impasse, but those negotiations have stalled for years.

Efforts to restart them this year failed, despite three rounds of face-to-face talks between representatives of Iran and the five permanent members of the Security Council, plus Germany.

Western powers suspect Iran is using to the programme to develop atomic weapons capability. Iran denies that and says its nuclear activities are purely peaceful.