Pope Benedict XVI has called on adults to "protect and to care for children" and sent a message to minors suffering from violence in a speech in the central Mexican city of Guanajuato.
In his first public event on his second day in Mexico, the pope made a special mention of Mexican children "who have to bear the burden of suffering, abandonment, violence or hunger."
Amid complaints from sexual abuse victims that the pope would not meet them in Mexico, Benedict referred to the mistreatment of children on Saturday, without specifically mentioning Catholic priest pedophilia scandals of recent decades.
"I wish to lift up my voice, inviting everyone to protect and to care for children, so that nothing may extinguish their smile, but that they may live in peace and look to the future with confidence," the pope said before hundreds of children at the Casa Del Conde Rul, where he earlier met with President Felipe Calderon.
In a country where violence is an open wound for many families, the pope also warned young people against revenge.
"The disciple of Jesus does not respond to evil with evil," he said.
The pope has faced criticism during the visit over the Vatican's management of Mexico's most notorious pedophile abuse offender, Marcial Maciel, the founder of the influential Legion of Christ order, who died in 2008.
Mexican victims of sexual abuse on Saturday accused the Vatican of protecting Maciel for decades and expressed frustration that Pope Benedict XVI would not meet them there.
On Sunday, the pope is due to hold a Mass in the city's Parque del Bicentenario, which is expected to be attended by hundreds of thousands of people.
Tens of thousands of people lined the streets as the pontiff's bulletproof popemobile passed through the city of Leon. Entire blocks exploding in yellow confetti and people chanted "Benedict, brother, you are now Mexican".
Some drug cartels had promised to halt acts of violence during the pope's visit, but at least 13 bodies were found throughout Mexico before Benedict's arrival, as a result of what the government called drug-related violence.
Seven men were shot along a road in Sinaloa and another four were found decapitated in Acapulco. A warning message to rival gangs was found alongside the severed heads.
"It is evident that Marxist ideology as it was conceived no longer responds to reality "
- Pope Benedict
Calderon and his conservative National Action Party (PAN), a group with strong Catholic roots, have invested huge political capital in trying to crack down on the gangs.
But the increasing death toll has eroded support for the PAN ahead of a July 1 presidential election, putting the main opposition Institutional Revolutionary Party, or PRI, in pole position to take the reins in Mexico.
The second leg of Benedict's six-day trip, beginning on Monday, takes him to Cuba.
On his flight to Mexico, Benedict told reporters that "it is evident that Marxist ideology as it was conceived no longer responds to reality," and he urged Cubans to "find new models, with patience, and in a constructive way."
The comment about Marxism was as blunt as anything his predecessor, John Paul II, made during his 1998 trip to Cuba, when the former pope called for the freeing of Cuba's political prisoners while condemning the US' blockade that makes the island nation's access to the international economy much more difficult.
Bruno Rodriguez, Cuba's foreign minister, defended the Caribbean island's ideology, calling the Cuban system "a democratic social project, genuinely chosen, which is constantly perfecting itself".
"We consider the exchange of ideas to be useful. Our people have deep convictions developed over the course of our history," Rodriguez said at a news conference. "Cuba will listen with all respect to his holiness."
Benedict's weeklong trip will be a test of stamina for the pope, who turns 85 next month. At the airport on Friday in Rome, he used a cane, apparently for the first time in public, as he walked about 100 metres to the airliner's steps.
Papal aides, speaking on condition of anonymity, said Benedict had been using the cane in private for about two months because it made him feel more secure, not for any medical reason.
Last autumn, Benedict started using a wheeled platform to navigate the vast spaces of St Peter's Basilica during ceremonies.