Filipino riot police blocked the entrance to a high-rise building that houses the Chinese consulate in Manila's financial district as around 200 protesters marched on the office.
The street action, which remained peaceful, came after deadly riots in Vietnam that Hanoi said were triggered by China's deployment of a deep-sea oil rig in a part of the South China Sea.
The protesters, some wearing green cardboard cut-outs of turtle shells, carried placards that read "Vietnam-Philippines join hands to kick off China", "China Stop Bullying Vietnam and the Philippines" and "We Support Vietnam".
The Philippines this week filed criminal charges against nine Chinese crew members of a fishing boat seized by Filipino police in the disputed waters for collecting hundreds of protected giant sea turtles.
The protesters also chanted "Paracels Vietnam", referring to the South China Sea island chain where the Chinese oil rig is deployed.
Filipino politicians joined members of Manila's Vietnamese community at the demonstration.
"We are here to protest what China is doing against Vietnam. We need to call on the support of local and international friends," Arya Nguyen, one of about 60 Philippines-based Vietnamese who joined the protest, told AFP.
"If they (the Chinese government) can do that to Vietnam, they can do it to everybody," echoed Janicee Buco, a Filipina representative of a community group called Vietnam Filipino Association.
Buco said the Vietnamese who took part were Philippines-based descendants of Vietnamese boat people who fled with the aim of being resettled in the West after the Vietnam war.
The protesters said they felt aggrieved over China's recent moves to assert its territorial claims over most of the strategic and resource-rich waters, including the oil-rig deployment that Hanoi said triggered ramming incidents involving Vietnamese and Chinese vessels.
Like the two communist rivals, the Philippines, Brunei, Malaysia and Taiwan also have claims to the sea, which overlap those of China and Vietnam.
Manila also accused Beijing of illegal land reclamation on a reef that Filipino officials said could be used to build China's first airstrip in the disputed waters.
Manila from time to time arrests Vietnamese fishermen for poaching in Filipino coastal waters, but bilateral ties are otherwise cordial.
Both nations have overlapping claims to the Spratly Islands in the South China Sea, but there has been little tension over those as they work together through ASEAN to contain China's territorial ambitions.
