"All European Union member states obviously stand united against accusations made towards individual EU countries and attempts to mark out the attitude of some of them towards Iran," said the statement by the EU presidency.
Iran has lashed out at "meddling" by Western nations and accused the foreign media, already facing tight restrictions on their work, of fomenting the unrest that followed the June 12 presidential election in Iran.
According to official results the poll was won by hardline incumbent Mahmoud Ahmadinejad by a large margin but his opponents have rejected the tally charging vote fraud and staged massive demonstrations in Tehran.
On Monday, riot police fired tear gas to break up an opposition rally in Tehran, witnesses said, as demonstrators defied a warning from the Revolutionary Guards that it would crush further protests.
"The EU, in full respect of the sovereignty of Iran, closely follows the development of the post-election situation in Iran, and expects the crisis to be settled through democratic dialogue and peaceful means," the statement said.
"The EU is deeply concerned with the continuing brutal violence against demonstrators which has so far resulted in the loss of lives," it said.
The 27-nation bloc also called on "the Iranian authorities to refrain from mass arbitrary arrests and strongly condemns all restrictions imposed on media and journalists."
The protests over the June 12 election are the biggest popular upheaval in Iran since the 1979 Islamic revolution.
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