To fend off global criticisms, China became positive about holding talks with ASEAN over relevant issues.
In a joint statement after their foreign ministers met on the sidelines of the gathering, the three countries criticised ongoing "land reclamation, construction of outposts, militarisation of disputed features" and said any code of conduct must be "legally binding, meaningful and effective".
"If there are still non-regional forces in the region, they don't want to see stability in the South China Sea and they still want to stir up trouble in the South China Sea, we need to stand together and we need to say no to them together", Wang said.
As a sign of the booming ties between China and the 10-country group, China has been Asean's largest trade partner for eight years.
China claims almost all of the sea, through which $5 trillion in annual shipping trade passes, and its artificial islands have raised concerns it could eventually build military bases there and establish de facto control over the waters.
She stressed that the U.S. shares concerns over the developments in the region that they consider to be "unconducive to regional stability, such as land reclamation".
Asean ministers are now meeting in Manila for the 50 ASEAN Foreign Ministers' Meeting.
US Secretary of State Rex Tillerson, Japanese Foreign Minister Taro Kono and Australian Foreign Minister Julie Bishop also called on Beijing to abide by a 2016 global tribunal ruling that invalidated its sweeping claims in the South China Sea. "In due time, China dropped that and said, "Let's approve the framework and let's go now to the COC", Mr Cayetano told reporters.
Japan had earlier criticised China's military build-up and reclamation work on islands in disputed areas of the South China Sea.
They also called on China and the Philippines to respect last year's ruling by an worldwide arbitration tribunal, which dismissed most of Beijing's claims to the sea.
An ASEAN declaration in 1992 called for a code of conduct for disputes involving the South China Sea, as did the 2002 joint declaration with China.
The communiqué of the 49th ASEAN Foreign Ministers' Meeting in Laos also called out against land reclamation and militarization.
There was no mention at all of the ruling a year ago of the Permanent Court of Arbitration in the Hague on the UN Convention on the Law of the Sea (UNCLOS) which rejected China's claim to sovereignty over most of the South China Sea.
"We expect nations not to tell us what to do", Foreign Secretary said at a news conference.
Several foreign ministers of the member states of the East Asia Summit and the 24th ASEAN Security Forum were attending meetings in Manila, where the main focus of the discussions was North Korea as well as the South China Sea.