Miliband said it would have been better for Britain to avoid its hasty decision on the issue and to wait until after a meeting of European Foreign ministers was held.
British Foreign Minister William Hague withdrew British diplomatic staff from Iran in November 29, 2011, following a protest outside the UK embassy in Tehran.
On November 27, Iranian lawmakers voted to downgrade diplomatic ties with Britain.
The move came in response to Britain’s decision to impose sanctions on the Central Bank of the Islamic Republic of Iran, over the false allegation that Tehran's nuclear program may consist of a covert military agenda.
Former British Foreign Secretary David Miliband has criticized the UK government policies, saying it was a mistake for Britain to close its embassy in the Iranian capital, Tehran.
Talking about Iran at Royal United Services Institute, Miliband said the decision to close down the British embassy in Iran was "not just regrettable but damaging",