A new report from the Mexican Catholic Multimedia Centre (CCM) says six priests have been killed and three others have been abducted in the last two years.
CCM is now calling on the Mexican government to provide "security in areas with a significant presence of organized crime".
According to the Vatican, Mexico is now the country with the most attacks on Roman Catholic religious leaders in the world.
The report outlines several reasons for attacks on priests and says their often outspoken views against gangs can put them in danger.
It also says churches are seen as attractive targets for extortion or money laundering, and that religious leaders who refuse to cooperate frequently come under threat.
Christian Solidarity Worldwide has also raised concerns about the increasing number of killings.
Chief executive Mervyn Thomas said: "The continued increase in the number of attacks on religious leaders in Mexico, making it one of the most dangerous places in the world for church leaders, is shocking and deeply concerning.
"We urge the Mexican government to implement effective strategies to provide security to civilian populations in areas with a strong influence of criminal groups, and to develop strategies to support civil society actors like churches and religious leaders as they come under threat.
"We urge the international community to engage with the Mexican government on these matters and to recognise the role that many religious leaders play, not only as leaders of their churches, but also as voices for peace, justice and integrity as human rights defenders."