Cited by the Xinhua news agency, Keqiang said the planned measures would "not only cause serious damage to related industries, enterprises and employment in China, but will also hurt the personal interests of users and consumers in Europe."
Keqiang said he hoped the EU would uphold the principles of free trade while keeping China-EU economic and trade relations in mind.
The critique, delivered in a speech to business and financial leaders during a visit to Switzerland , echoes previous warnings by China, which has threatened the EU it will take "assertive measures" to defend its interests.
The two sides are embroiled in tit-for-tat trade disputes on items ranging from agricultural products to steel tubes, highlighting growing trade tensions amid financial uncertainties around the world.
Last week, the European Commission said it would open an anti-dumping and anti-subsidy investigation into mobile telecommunications network equipment and components from China if bilateral negotiations fail.
Earlier this month, the European Commission approved imposing a custom duty of 47 percent on China-made solar panel products to protect European manufacturers.
Keqiang warned that if the EU goes ahead with the moves, it risks promoting protectionism and may harm Chinese companies and employment.
"In the current economic circumstances all countries should strive to maintain a stable and open international trade environment and be cautious in using trade remedy measures."
China is the world's second-largest economy and the EU is its biggest trading partner.
In an apparent retaliatory move, Beijing's commerce ministry in November launched an anti-dumping and anti-subsidy investigation into solar-grade polysilicon from the EU, a key material used to make solar cells.
It also recently opened an anti-dumping probe into some seamless steel pipes from the EU and other markets, after slapping punitive taxes on another type of steel tube imports from the region and Japan.