Coalition for Reforms and Democracy leader Raila Odinga on Tuesday claimed police used live bullets to disperse anti-IEBC protesters along University Way in Nairobi on Monday.
The Cord leader said some of the protesters may have been injured during the scuffle between the protesters and the police deployed to guard the IEBC offices at Anniversary Towers.
"Some of our people may have sustained injuries as a result of the live bullets and the teargas that police fired but nobody must give up," he said in a statement.
"We must soldier on. Nothing comes easy and we are under no illusion that change at the IEBC will come easy. But it will come."
Police on Monday fired gunshots and used teargas to disperse opposition supporters who had accompanied Mr Odinga, Kalonzo Musyoka (Wiper) and Moses Wetangula (Ford Kenya) to the IEBC head office to force the electoral body's commissioners quit office.
General Service Unit and anti-riot police were deployed to deal with protesters in case they turned violent.
"We are acting within the rights in Article 37 and 38 of our Constitution," the opposition chief said.
"And to those arguing that we must go to Parliament if we want change, let us remind them that all sovereign power belongs to the people of Kenya."
"The people may exercise their sovereign power either directly or through their democratically elected representatives. In the case of removal of IEBC commissioners, the people have decided to exercise their sovereignty directly."
"We therefore today (Tuesday) give notice that unless the IEBC Commissioners vacate office now or immediately and unless there is established an inclusive mechanism for structured dialogue put in place, again, immediately we will continue to organise demonstrations and protest rallies countrywide on every succeeding Monday until our conditions are met."
After Monday's demonstration, a section of lawmakers led by Senator Prof Anyang Nyong'o criticized the police for using excessive force against unarmed civilians peacefully protesting.
MCAs from Kisumu also criticized police for dispersing demonstrators during the Monday protest.