The protestors are demanding that the pop diva's shows in Manila be canceled. A group called Biblemode Youth Philippines says Gaga's music, in particular her song "Judas", mocks Jesus Christ.
The group says it will file a lawsuit against the singer if she sings the song at the concerts on Monday and Tuesday.
Former Manila Mayor Jose Atienza said the singer and organizers can be punished for offending race or religion. The penalty can range from six months to six years in prison, although no one has been convicted recently.
Lady Gaga recently scrapped a concert in Indonesia after protests from conservative Muslims. In Seoul, fans under 18 were banned from her concerts over complaints that her lyrics and costumes were too sexually provocative.
The Associated Press contributed to this report.