President Salvador Panelo said doing so would “cause irritants” that threaten the currently positive relationship with Beijing. His comments follow an increased Chinese military presence around the Philippine island of Pag-asa. China previously warned “non-littoral states” that are in the disputed sea against “stirring up trouble”.
China’s warning follows the US’s naval ships participating in drills alongside the Philippines.
Both countries practised recapturing small islands seized by a hypothetical foreign military force.
In the exercises, the US also tested a new application for its amphibious assault ships.
The US Navy said in a statement: “US and Philippine forces will conduct amphibious operations, live-fire training, urban operations, aviation operations, and counterterrorism response.
“The ship and its fighters represent an increase in military capability committed to a free and open Indo-Pacific region.”
Tensions in the South China Sea have risen in the past year as the US tries to push back China’s hold on the region.
The waters are the world’s busiest trade route is also claimed by the likes of Vietnam, the Philippines and Brunei.
So far, the US has conducted 15 freedom of navigation operations in the area since 2015.
The US also want allies to consider similar manoeuvres.
Mike Pompeo, the US secretary of state, told an audience at the National Review Institute’s 2019 Ideas Summit that “there is an important relationship between the US and China”.
But he added: “Their moving into the South China Sea is not because they want freedom of navigation.
“Their efforts to build ports around the world aren’t because they want to be good shipbuilders and stewards of waterways, but rather they have a state national security element to each and every one of them.”