The sale would send a wrong message to "Taiwan independence" forces, China's embassy in Washington said in a statement.
China has urged the US to revoke immediately it's "wrong decision" to sell Taiwan $1.42 billion worth of arms, saying it contradicted a "consensus" President Xi Jinping reached with his counterpart, Donald Trump, in talks in April in Florida.
The sales would send a very wrong message to "Taiwan independence" forces, China's embassy in Washington said in a statement.
TRT World's Dan Epstein has the latest.
A US State Department spokesperson said on Thursday the administration had told Congress of seven proposed sales to Taiwan, the first under the Trump administration.
"The Chinese government and Chinese people have every right to be outraged," the embassy said.
China regards self-ruled Taiwan as a wayward province and has never renounced the use of force to bring it under its control. China's Nationalists fled to the island after losing the civil war with China's Communists in 1949.
The US is the sole arms supplier to Taiwan.
Taiwan a "core issue" in Sino-US ties
China's Defence Ministry said Taiwan was the "most important, most sensitive core issue in Sino-US ties," warning the US to end such sales to avoid further damaging peace and stability in the Taiwan Strait.
Trump was critical of China during his successful 2016 presidential campaign but his meeting at his Mar-a-Lago resort in Florida with Xi raised hopes for warmer relations.
Trump later played up his personal relationship with Xi, calling him a "good man," and stressed the need for China's help in reining in a defiant North Korea's development of nuclear weapons and missiles.
China's anger over the US plan to supply Taiwan with weapons risks undermining Trump's attempts to press China to help on North Korea.
The proposed US package for Taiwan includes technical support for early warning radar, high-speed anti-radiation missiles, torpedoes and missile components.
Frosty relations with Taiwan
Beijing's relationship with Taiwan has been frosty since President Tsai Ing-wen took power in Taipei last year. Tsai leads an independence-leaning party that refuses to recognise Beijing's "one China" policy.
Tsai's office said on Friday the planned sales increased Taiwan's confidence and ability to maintain peace and stability across the Taiwan Strait.
The sales, which require congressional approval, would be the first since a $1.83 billion sale that former president Barack Obama announced in December 2015, also to China's dismay.
The previous package included two navy frigates in addition to anti-tank missiles and amphibious attack vehicles.