Britain has no intention of inciting a revolution in Iran or any other activity which would undermine that country, the Foreign Office has said, BBC reported.
And a spokesman said the trial of a British embassy worker in Tehran, accused of spying and inciting unrest, was due to "gross misinterpretation".
UK Foreign Secretary David Miliband has described the charges against Iranian Hossein Rassam as unjustified.
Nine embassy officials were held after protests over June's election result.
There were demonstrations in Tehran and other cities when President Mahmoud Ahmadinejad was returned for a second term in office.
'No contradiction'
The Foreign Office said Mr Rassam's trial rested on "a gross misinterpretation of what constitutes legitimate activity for embassies and their foreign and local staff in any country in the world".
It was essential for diplomats to fully understand the country in which they were posted, the spokesman added, "and the only way to do this" was for them to meet politicians from different sides, journalists and other public figures.
"To help in that task, it is entirely normal to have local staff whose experience allows diplomats to understand events and to help them meet influential people.
"There is no contradiction between being a patriotic and honourable Iranian and working in this capacity for a foreign embassy in Iran."
"Britain is not engaged in any plot to undermine the Islamic Republic of Iran through a so-called velvet revolution or any other means," the Foreign Office spokesman said.
"The indictment does not present any evidence to support this supposition."
Iran's rulers have has repeatedly accused foreign powers - especially Britain and the US - of playing a part in encouraging last month's demonstrations.
Opposition candidate Mir Hossein Mousavi said the vote was rigged in favour of Mr Ahmadinejad, a claim rejected by the president and Iran's main election body, the Council of Guardians.
Anger at the result led to the largest mass protests seen in Iran since the revolution in 1979 which brought the current Islamic regime to power.