Iran's defeated presidential candidate, Mir-Hossein Mousavi called for re-election on Wednesday in Tehran.
He said that a recount was not enough and that new elections were needed.
Mass demonstrations have been reported in cities like Isfahan, Shiraz and Mashad since last Friday's presidential election. It is the largest mass protests in the country's history since the 1979 revolution.
Iran police has continued arresting Pro-reform intellectuals and journalists. The authorities accused the demonstrators of being manipulated by the outside world.
For last Friday's presidential election, official results released on Saturday had given Ahmadinejad 63% of the vote against 34% for Mousavi.
Mousavi, who earlier challenged the outcome, convinced the Supreme leader and the Guardian Council to agree to a recount in some regions. He called on his supporters to come out for another demonstration and a day of mourning.
On Monday unknown gunmen shot at crowds, killing at least seven people. Mousavi urged his supporters to gather in mosques and hold peaceful rallies to comfort the families of martyrs and the wounded.
Despite the rising tide of unrest the authorities have not let up on their crackdown against pro-reform, pro-Mousavi politicians and journalists.
Some foreign journalists have been deported, but many others have been able to slip through the authorities' tight controls.
The authorities have tried to block TV, radio, satellite phones and the internet but demonstrators have been to communicate with the outside world via text messaging and video uploaded on YouTube.