Tens of thousands in Algeria have gone to the streets angrily because 81-year-old President Abdelaziz Bouteflica had the plan to seek a fifth term.
Police bombarded demonstrators in the capital Algiers with tear gas.
According to authorities, seven demonstrators and more than 50 officers were injured and 45 people were arrested.
Protests against the government are rare in Algeria, but several broke out after Mr Bouteflika confirmed his candidacy.
He has rarely been seen in public since a stroke in 2013 and is currently under medical examination in Switzerland.
As they marched through the streets of Algiers on Friday, some protesters wore banners saying "Leave means to go." Others said their intentions were peaceful.
"20 years is enough," said a woman cited by the AFP News Agency, who had teamed with her husband and children.
"This is a celebration, not a protest," Ali Selmi told Reuters. "We celebrate the rebirth of Algeria."
Some demonstrators threw stones near the presidential palace and were pushed back by the police with tear gas. Witnesses said there were injuries on both sides.
Demonstrations also took place after Friday prayers in several other cities in Algeria.
Mr Bouteflika came to power in 1999 and is acknowledged to have ended a civil war that killed more than 100,000 people.
Protests against food prices and unemployment broke out during the Arab Spring in 2011, but he reacted by lifting a nearly two-decade-old state of emergency and responded to a major demand from the demonstrators.
After his stroke, he won re-election in an opposition-praised poll and dissolved the country's powerful espionage agency.
Critics say his health means he can not fulfill his duties as president.
Mr Bouteflika is still very much inclined to win the elections in April despite the demonstration of disagreement.