Tesla chief executive Elon Musk was in China in January for the groundbreaking of the factory, where he said he planned to approach local banks for the money to get the plant built and into production.
Tesla shares rose more than two per cent in after-hours NY trading.
Their new lawsuit, filed in Delaware Chancery Court, seeks to permanently block Musk's "unchecked use of Twitter to make inaccurate statements about the company", lawyers for one of the investors, the Laborers' District Council and Contractors' Pension Fund of OH, said in a statement.
According to a filing by Tesla, as much as $520M in loans have been committed by Chinese banks.
Tesla's China borrowing follows its biggest ever debt payment recently.
After years of negotiations with Chinese authorities to become the first foreign automaker to wholly own a manufacturing facility in the country, Tesla broke ground on the outskirts of Shanghai on Jan 7.
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In January, Tesla in Shanghai and production is expected to begin in the second half of this year.
China is by far the world's biggest vehicle market and sales there have been on an upwards trajectory for years, although they slipped 2.8 percent last year.
Retail sales of sedans, sport utility vehicles, multi-purpose vehicles and minivans fell 18.5% to 1.19 million units last month, according to the China Passenger Car Association Friday.
In the broader slowdown, battery-powered autos had been an exception.
Local manufacturing also will help the company sidestep any re-escalation of trade tensions between the U.S. and China. The amendment also doubled the letter of credit subfacility to 400 million from 200 million USA dollars.