Rev. Hugo Valdemar, spokesman for the Catholic Archdiocese of Mexico City, urged lawmakers to listen to their "conscience" and oppose the initiative.
This is the fourth jurisdiction nationwide where gay couples can automatically get married, along with Coahuila, Quintana Roo and Mexico City.
The Supreme Court announced Friday that same-sex marriage is legal across the U.S.
'Today is a big step in our march toward equality. Gay and lesbian couples now have the right to marry, just like anyone else. #LoveWins.' the U.S. president tweeted.
The position dissolves the meaning of marriage, according to the institution.
The court's ruling is considered a 'jurisprudential thesis' and does not invalidate any state laws, meaning gay couples denied the right to wed would have to turn to the courts individually.