China's state-run media said the Taiwan Travel Act signed by President Donald Trump could lead to military pressure.
The law, which allows official visits between the two countries, has angered China as it considers Taiwan one of its provinces and regularly holds military drills near the island.
The warning comes as relations between the US and China deteriorate over tariffs and a potential trade war.
China could respond to a law that encourages relations between the US and Taiwan with "military pressure", the country’s state-run media said on Sunday.
On Friday President Donald Trump signed the Taiwan Travel Act, which went into effect the following day, encouraging visits between the United States and Taiwan at all levels. The US ended diplomatic relations with Taiwan in 1979 but continues to have a "robust unofficial relationship" with the self-ruled, democratic island, that Beijing considers a province of China.
"China will and should take timely countermeasures against the US and all "Taiwan independence" secessionist forces through diplomatic and military means if US legislation that encourages high-level contact between the US and the island of Taiwan is implemented," China’s English language Global Times reported.
The paper, an offshoot of the People’s Daily, cited a former major general in the Chinese army and Liu Weidong, an expert in US relations at a government-run research institute. And given the publication’s close links to Beijing, the views likely align with those in power.
The Chinese embassy in Washington initially responded on Friday saying the law "severely violates" the "political foundation of the China-U.S. relationship" and its "one-China" approach to Taiwan.
In 2005, China created an anti-secession law that allows the country to use "non-peaceful means" to prevent Taiwan establishing independence.
"If any 'Taiwan independence' secessionist forces perceive the US bill as a 'pro-independence' signal, the Chinese army will resume its military probes circling the island and send more military vessels and airplanes to patrol the Straits," Global Times quoted Liu as saying.
China regularly carries out military drills near Taiwan, which has been a cause for concern internationally. Last year, China conducted 16 drills near Taiwan and a report from the island's defense department said China's "military threat towards us grows daily."
China may also take diplomatic action against the US, Global Times said, including stopping high-ranking official visits to Washington for a set time.
High-level diplomatic relations between the two countries appear to be getting more strained by the day.
The heightened tensions between China and the US come after Trump signed a law in December allowing US navy ships to visit Taiwan. China previously said any such visits could provoke war.
Trump also appeared to target China with new tariffs on steel and aluminum. In response, China warned the US that trade wars "harm the initiator" and is thought to be considering responding with its own tariffs.