Iran's foreign minister, Ali Akbar Salehi, on Sunday reiterated that he regretted November's storming of the British embassy in Tehran, but asserted that the incident was "not foreseeable."
"The incursion into the embassy was not foreseeable... The protest had the necessary permission and was supposed to be held within the law," he said, according to the Mehr news agency.
"However, we regret what happened, which in my view was not called for," he was quoted as saying.
Britain closed its embassy in Tehran the day after the November 29 assault on the mission by Iranian pro-regime protesters, saying that they could have only acted with the consent of the Iranian authorities.
It also ordered Iran's embassy in London closed, and reduced diplomatic ties to the minimum.
International outrage at the attack was widespread and raised already high tensions over Iran's controversial nuclear programme.
Iranian officials, who supported the demonstration in front of the British embassy to express anger over new Western sanctions levelled at Tehran, have been sending mixed messages over the storming of the embassy.
Salehi and the foreign ministry from the start expressed regret at the attack.
But parliamentary speaker Ali Larijani and influential clerics have defended the protesters' actions, saying they were furious at decades of British meddling in Iran.
President Mahmoud Ahmadinejad and other top leaders have stayed silent on the attack.
Salehi implied that British officials had overreacted by withdrawing its diplomats from Tehran, accusing them of "becoming more Catholic than the Pope," according to Mehr.
He also criticised Britain's decision to cut off all contact with Iran's financial sector, including its central bank, as part of the new unilateral sanctions.