China also accused Washington of greatly exaggerating the incident
China said the US is 'hyping up' the incident in which they seized a sea drone from the country.
Earlier this week, a Chinese warship seized a US Navy underwater drone collecting scientific data in the South China Sea.
Donald Trump said the US should let China keep the underwater drone, writing on Twitter: "We should tell China that we don't want the drone they stole back.- let them keep it!"
His message came after the US military announced it had reached an understanding with Beijing for the return of the underwater glider, which China said it seized to ensure the "safe navigation of passing ships".
Earlier on Saturday, Mr Trump used Twitter to criticise China, slamming the move as an "unpresidented (sic) act". He later corrected the spelling.
Washington said the drone was collecting scientific data in the disputed South China Sea, and was one of two being recovered by a survey ship, when it was taken by a Chinese warship on Thursday.
On Saturday evening, the Pentagon said that after "direct engagement with Chinese authorities" it had "secured an understanding" that the 10ft-long unmanned glider would be returned.
The US oceanographic survey ship, USNS Bowditch, was positioned about 50 nautical miles northwest of Subic Bay, near the Philippines.
When the Chinese warship approached and seized the drone, the two vessels were 500m apart.
No shots were fired and the Chinese ship left with the drone.
Tensions between the US and China have escalated since Mr Trump's shock election victory, with the President-elect suggesting he is willing to abandon the "One China" policy which guides Washington's position on Taiwan.
Mr Trump caused outrage in Beijing after he took a call from Tsai Ing-wen, the President of democratically self-ruling Taiwan, which China views as a rogue province awaiting unification.