Iran's supreme leader Ayatollah Ali Khamenei has said the nation "will not yield to pressure" over a disputed presidential election, BBC reported.
Several people have been killed in days of street protests since the 12 June election returned Mahmoud Ahmadinejad to the presidency.
Violence erupted after protesters claimed the elections were rigged.
Iran has also said it is "reviewing" whether to downgrade relations with UK, as diplomatic tensions increase.
Iranian riot police and militiamen appear to have put a halt to protests in the capital, in which official say 17 people have killed.
There are reports that a further rally is planned for later on Wednesday, and there have been calls for a day or more of mourning from Thursday.
The ayatollah, whose earlier command to stop protesting went unheeded, said: "I had insisted and will insist on implementing the law on the election issue.
He added: "Neither the establishment nor the nation will yield to pressure at any cost."
He had earlier agreed to extend by five days the amount of time allowed to examine complaints of electoral fraud.
However, the Guardian Council, Iran's electoral body, said there was "no major fraud or breach in the election".
Iran 'will not yield' over poll
