Iranian foreign ministry's spokesman Bahram Qasemi said that deputy Foreign Minister Abbas Araqchi has handed a strongly worded protest note to the British ambassador in Tehran demanding protection for the Iranian embassy and its diplomats and staff, reported Tasnim news agency from Tehran.
Scotland Yard said the protesters were arrested on suspicion of causing criminal damage and being on diplomatic territory unlawfully.
"All four males have been taken to a central London police station, where they remain in custody".
Images posted on social media showed four men in black attire on the balcony of the embassy, waving a blue and white flag.
Shiite cleric Grand Ayatollah Sadegh Hossein Shirazi, whose son was recently arrested for insulting Iran's Supreme Leader Ayatollah Ali Khamenei, has been a fierce critic of Iran's clerical leadership.
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The official wasn't authorized to discuss the investigation and spoke on condition of anonymity because no arrests have been made. Leading the charge is 50 Cent who is arguably the biggest troll on Instagram. "LOL", with the running man and dash emojis.
The Iranian Foreign Ministry reportedly sent a letter to the British embassy in Tehran complaining about the slow security response by London police, citing reports that they took no action for several hours after the attack.
Friday's raid on Iran's embassy building in London by members of the Shirazi cult was a flagrant violation of global law and laid bare the true image of its deviated ideology, Iran's ambassador to Britain said.
In 1980, gunmen seized the embassy to try to secure the release of Iranian political prisoners.
He also said, "In my opinion, this incident will not affect the relations between the two countries, because the British government and police forces' stand has been clear in this respect, and we expect to be informed about details of the incident".
Baeidinejad said that the assailants were carrying knives and sticks and chanted slogans against Iranian officials and using bad language against Abu Bakr, Umar, Uthman (the caliphs of Mecca) and Aisha, the wife of Prophet Mohammad (S).