The United States' allies in Europe have criticised its recent decisions to restrict oil trade with Iran and to limit the extension of waivers for nuclear non-proliferation projects.

"We ... take note with regret and concern of the decision by the United States not to extend waivers with regards to trade in oil with Iran," Britain's foreign office said in a joint statement with its German and French counterparts and the European Union.

"We also note with concern the decision by the United States not to fully renew waivers for nuclear non-proliferation projects," Britain's foreign office added.

Washington acted on Friday to force Iran to stop producing low-enriched uranium and expanding its only nuclear power plant, intensifying a campaign aimed at halting Tehran's ballistic missile programme and curbing its regional power.

Last week, the United States said it would stop waivers for countries buying Iranian oil, in an attempt to reduce Iran's oil exports to zero.