"Protectionism would be damaging to the global economy and the concerned economies as well," Wolfgang Schaeuble said.

"The process has begun long ago, but it really formally begins on Wednesday," Trump said during a visit to the U.S. Treasury Department.

The announcement followed media reports that Exxon had sought a waiver to resume a joint venture with Russia's Rosneft oil company.

Heads of the Republic, Bright Armenia and Civil Contract - the parties that make up the bloc - took part in a campaign rally.