Nabeel Masih, 16, is accused of blasphemy charges for clicking the like button under an image of the Kaaba in Mecca, one of the holiest sites in Islam.
A Muslim alerted officers to the post saying he found it insulting to his religion, police said.
The teenager has been held in custody ahead of a trial. If found guilty he could face the death penalty.
It's believed police removed the image from the social networking site so it is now impossible for the teen to prove what was, or wasn't, written.
Naveed Aziz, British Pakistani Christian Association investigator, said: "Local people have told me that apparently the image of the Islamic Kaaba was shown on Nabeel's Facebook profile, showing the image of a pig on top.
"This infuriated local Muslims who then reported the crime to local police."
Local Christian man Dr Nazeer Gill is quoted by the British Pakistani Christian Association as saying: "All the local Christian community is very frightened, we are also saddened that such a young boy is now facing a potential death sentence.
"We will be praying for peace and all church leaders will be doing their utmost to broker peace so that innocent people are not killed or attacked in the aftermath of this incident. Please pray for us."
Pakistan's blasphemy laws mean anyone accused of insulting Islam can be sentenced to death. The laws are often used by Muslims to settle personal scores.
Asia Bibi is one of the most high profile victims of the law. The Christian mother was sentenced to death in 2010 for allegedly insulting the Prophet Mohammed during a discussion with Muslim women.
She is exploring her final appeal option before she is put to death.