The Embassy of the United Kingdom in Iran was ransacked on Tuesday. British flags were burned and offices were left in shambles.
Iran says hundreds of pro-government students were responsible for the attack.
Prime Minister of the UK David Cameron condemned Iran for not defending British staff. The US, Germany, France and the EU also condemned the attack.
Iran says they regret the incident. They urge that police tried but were unsuccessful in stopping the assailants.
The demonstrations followed a vote in Iran’s parliament to reduce diplomatic ties with the UK. This vote came as a response to the UK’s decision last week to impose new sanctions on Iran for continuing its nuclear programme.
The US and Canada have also threatened Iran with sanctions. They say Iran has been developing nuclear weapons. But Iran insists that their nuclear programme is for energy use only.