"The (EU) Council remains very concerned about the humanitarian, political and economic situation in Zimbabwe and conditions on the ground," it said in a statement agreed by foreign ministers at a meeting in Brussels.
"(It) may endanger the holding of free and fair parliamentary and presidential elections," the statement said, urging veteran President Robert Mugabe to ensure the elections respect international standards.
The March 29 election presents Mugabe with one of the biggest challenges to his rule since taking office in 1980.
Millions of Zimbabweans hoping for an end to a decade-long economic crisis are due to vote in presidential, parliamentary and municipal elections described by Mugabe and his opponents as a landmark poll in the post-independence period.
EU relations with Zimbabwe have been tense for years, and have been a thorn in EU-Africa relations.
The 27-nation bloc slapped visa bans and asset freezes on Mugabe and over a hundred top officials after a controversial distribution of white-owned commercial farms to mainly landless blacks and Mugabe's disputed re-election in 2002.
"We want to see elections that are properly free and fair in Zimbabwe," said British Foreign Secretary David Miliband. "The voice of the people of Zimbabwe needs to be heard in free and fair elections."