Cayetano assured that he already clarified this with member states of the Association of Southeast Asian Nations (ASEAN) and the world powers.
According to the secretary, the South China Sea issue was one aspect of ASEAN with China and it was not needed for other ASEAN countries to have a position on this.
Washington is not among the claimants to the waterway, among the busiest in the world, but it has declared it has a national interest in ensuring freedom of navigation and overflight and the peaceful resolution of the disputes.
"It's our policy to settle disputes in the East Sea through peaceful negotiations and with respect for diplomatic and legal process in accordance with global law, including the United Nations Convention on the Law of the Sea", he said, referring to the South China Sea.
Chinese President Xi Jinping sought to allay concerns over Beijing's military buildup and the prospects of war in the South China Sea's contested waters. Several nations back an active American military presence in the region to serve as a counterweight to China's increasingly assertive actions, including the construction of seven man-made islands equipped with military installations.
Ahead of the ASEAN summit, Duterte said at a ceremony that "the South China Sea is better left untouched, nobody can afford to go to war".
"He acknowledged that war can not be promoted by anybody, (that) it would only mean destruction for all of us", Duterte said in a news conference after flying back to Manila.
The disputed waters were among the issues discussed during the 20th ASEAN-China Summit, which is part of the 31st ASEAN summit and related summits chaired by the Philippines this year.
The regional bloc raised the issue of China's militarization during its meeting with the United States, a day after US President Donald Trump offered to mediate between claimant parties.
"The visit marks a new step forward in Vietnam-China relations", he said.
At the meeting's formal opening on Monday, Duterte made no mention of the South China Sea and pointed to other triggers for a threat of violence in the region.
Vietnam has become the most vocal opponent of China's moves after Philippine President Rodrigo Duterte softened his country's stance on China. I have done plenty of it from both sides. The dispute centers around the Spratly and Paracel Islands.
Duterte has courted Chinese trade and assistance and taken a non-confrontational approach to their territorial disputes.
"We have to be able to separate, to expect these sovereignty claims".