Over the past 24 months, Chinese authorities have been waging a campaign to remove crosses from churches and other buildings in the country.
The Christian symbols have been removed from hundreds of buildings, particularly in the Zhejiang province, with the authorities citing health and safety reasons.
The president said that China needs to be on guard against other religious influences from abroad.
The comments come as the country has made laws stricter on wearing veils and beards in the mainly Muslim region of Xinjiang, as well as the removal of crosses
Xi Jinping, speaking at a religious conference, said: "We must resolutely guard against overseas infiltrations via religious means and prevent ideological infringement by extremists," according to the official Xinhua News Agency.
He emphasised that religious groups need to listen to the official Communist Party, saying: "In no way should religions interfere with government administration, judiciary and education."