Women demanding that Mexico legalize abortion nationwide clashed with police in the capital, Mexico City, on Monday.
Police fired tear gas at groups of protesters, some of whom reportedly threw projectiles, including bottles.
The government said nearly a dozen police were injured in the melee. Protesters said they were victims of police brutality.
The demonstration in the mostly Catholic country came on International Safe Abortion Day.
Abortion is only legal in Mexico City and the southern state of Oaxaca during the first 12 weeks of pregnancy.
Abortion is only allowed in the rest of the country under limited circumstances, such as if a woman has been raped.