Authorities have in recent months increased restrictions on virtual private networks (VPNs), used to circumvent China's vast censorship apparatus known as the Great Firewall which blocks websites such as YouTube and Facebook.
Access to Google's email service also became more difficult in December.
The European Union Chamber of Commerce in China said the restrictions amount to an "Internet tax", adding that 86 percent of respondents to an internal survey said they had a "negative effect" on business, a 15 percent increase compared to June.
"This is not just a problem for international business we know from extensive conversations with the Chinese public and the private sector that many domestic companies are just as frustrated."
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Since Xi assumed power in 2012, free expression has been heavily curtailed and online censorship has sharply increased in order to maintain the ruling Communist Party's grip on power.
Of the companies surveyed by the lobby group, 80 percent said the tightening Internet controls has become worse since the start of 2015.
Some 13 percent of respondents said the recent increase in censorship means they have deferred or are unwilling to set up research and development centres in China which would be a blow to government plans to increase innovation.
Hua Chunying, a foreign ministry spokeswoman, said at a regularly scheduled news conference in Beijing that China "is open to foreign companies so long as they abide by China regulations".
The report comes just one day after an American Chamber of Commerce in China survey found 57 percent of respondents believed foreign firms are being singled out by Beijing's pricing, anti-monopoly, and anti-corruption campaigns.