BRUSSELS, May 31 (Xinhua) -- The European Parliament on Thursday condemned the United States decision to impose steel and aluminum tariffs on the European Union, urging the European Union (EU) to react "immediately with a firm but proportionate" response.

"I am very disappointed with the U.S. decision to impose duties on steel and aluminium imports from Europe. These are unilateral and unjustified measures that will do serious harm to workers, industry and consumers on both sides of the Atlantic," President of the European Parliament Antonio Tajani said in a statement.

"The European Union is ready to defend the interests of its citizens with all the means at its disposal. The European Parliament will play a full role in defending legitimate European interests," he added.

Tajani warned that the history of international trade shows that "protectionism is a negative sum game", that suits no one and only "risks triggering trade wars" that are harmful to everyone.

"The European Union plays by the rules. We will continue to promote open markets with all relevant partners on an equal footing, with high standards of worker protection, safety, consumer protection and intellectual property," he added.

"The International Trade Committee of the European Parliament condemns the decision of the United States to levy tariffs on imports of steel and aluminium from the EU. We fully support the European Commission in its stance against the arbitrary duties that clearly contradict WTO rules," Chairman of International Trade Committee of the European Parliament Bernd Lange said in a statement.

He urged the EU to react "immediately with a firm but proportionate" response. "Unfair trade must be fought in the WTO and in the G20 Global Forum on Steel Excess Capacity. Reforms of trade rules are possible, but through negotiations in these fora and not through unilateral measures," Lange said.

"The EU has consistently shown willingness to discuss with the U.S. the trade issues of interest to both sides, but has also made clear that we will not negotiate under threat. We call on Member States to ensure an EU-wide unity in our response to protect our citizens," Lange added.

U.S. Commerce Secretary Wilbur Ross said on Thursday that U.S. President Donald Trump has decided not to extend the temporary steel and aluminum tariff exemptions for the European Union (EU), Canada and Mexico and those tariffs on steel and aluminum imports from the threes key trading partners will take effect from Friday.