Lodewijk Briet said in a statement that the European Commission welcomed opposition leader Morgan Tsvangirai’s decision to join the unity government as prime minister.
"While we underline that this is a positive development, it does not itself spell the end of the political, economic and humanitarian crises Zimbabwe finds itself in," he said.
"This first step towards normalising the situation in Zimbabwe must be underpinned by clear confidence building measures by the new government," the statement said.
"In this light, we consider calls for the immediate lifting of the EU’s targeted measures to be premature and would first encourage all parties to comply fully with the terms of the power-sharing agreement," Briet said.
He reiterated that the EU sanctions do not target Zimbabwe’s population but "a defined number of people and companies that have been clearly linked to the government and the failure to respect basic human rights and democratic practice."
The sanctions are limited to travel restrictions and asset freezes, he said.
"The EU remains the main provider of humanitarian and essential development assistance to Zimbabwe," giving nearly 90 million euros (116 million dollars) annually.
The African Union and South Africa at the weekend called for the lifting of sanctions against Zimbabwe, following Tsvangirai’s decision to join the government.
The unity government has stalled for months following bickering over allocation of key ministries, including home affairs, which oversees the police.