Manila recently granted Washington access to more Filipino military bases as the allies seek to counter China's growing assertiveness in the region and its sweeping claims over disputed waters, islands and shoals, TRT World reported.
"We will not encourage any provocative action that will involve the Philippines by any other country," Marcos told reporters on Sunday aboard a plane en route to Washington.
"We will not allow the Philippines to be used as a staging post for any kind of military action."
Marcos's visit comes after the United States called on China to stop "provocative and unsafe conduct" in the contested South China Sea following a near-collision with a Philippine coast guard vessel.
Manila and Washington are bound by a 1951 mutual defense pact.
The April 23 incident was "a near-crash and that... can cause casualties on both sides," Marcos said on the flight, according to a statement by the Philippine presidential palace.
"That's exactly what we want to avoid," he added.
SKH/PR