Iranian supreme leader Ayatollah Ali Khamenei has insisted parliamentary elections due later this month should go ahead as planned.
Ayatollah Khamenei has ruled out postponing the polls
The government argues they should be delayed because conditions are not right for a free and fair election.
Mr Khamenei was speaking after talks between the hardline Guardian Council and senior politicians failed.
He said the 20 February polls would not be "delayed by even one day" and warned against "un-Islamic" protests.
The BBC's Middle East analyst, Roger Hardy, notes that Iranians should be celebrating the 25th anniversary of the revolution which overthrew its US-backed monarchy and replaced it with a radical and fiercely anti-American Islamic republic.
Instead, he says, their country is in constitutional chaos and its political institutions are gridlocked, with reformists on the ropes and their followers deeply demoralised.
More than 2,000 reformist allies of President Muhammad Khatami have been barred from taking part in the vote.
The conservatives are now confident they can deliver the knock-out blow by recapturing control of parliament and re-taking the presidency once Mr Khatami stands down at the end of his second term.
IRAN'S REINS OF POWER
Supreme leader Ayatollah Ali Khamenei: Appointed for life, overrides all other authorities (pictured above)
Guardian Council: Half chosen by Khamenei, responsible for vetting election candidates and laws
President Mohammad Khatami: Elected for four years, power can be circumscribed by clerics
Parliament: 290 members introduce and pass laws, subject to approval
In calling for the elections to go ahead as scheduled, Ayatollah Khamenei argued there was "no knot which cannot be untied".
But he also warned reformists not to advance their case too far by threatening to resign over the election dispute.
"Evading responsibility by resigning or any other method is illegal and religiously forbidden", he said.
On Sunday, more than 120 members of parliament resigned in protest over the vote row.
They said that the mass disqualification by the hardline Guardian Council only served to dissuade an already politically disillusioned public from voting.
The Guardian Council is an unelected overview body dominated by religious hardliners.
But there are now signs of a compromise, with the Council expected to announce that many of those barred from the election race may now run.
It is not clear if the deal will be enough to satisfy reformist MPs.
They have insisted that not only should all the bans be overturned but also that the vote should be postponed to give all candidates enough time to conduct their campaigns.