Olli Rehn, the EU enlargement commissioner, said "the Commission is ready to resume negotiations as soon as Serbia achieves full cooperation" with the ICTY.
Rehn said that if Mladic is apprehended very soon, a Stabilization and Accession Agreement could be concluded this year.
A Stablization and Accession Agreement is an essential step on Serbia's path toward eventual EU membership.
The EU's move has already produced a political casualty in Serbia. The country's deputy prime minister and its chief negotiator with the EU, Miroljub Labus, resigned, saying that the government had betrayed the interests of the country.
The government was also attacked by the ICTY's chief prosecutor, Carla Del Ponte, who, at a press conference called after the EU's decision, accused Serbia of misleading her.
Del Ponte said she had received reports that Belgrade could have arrested Mladic at the end of January but had declined to do so because the government wanted him to surrender voluntarily.
"The information which was presented to me at that time to substantiate that the positive outcome could be expected soon, has proven to be wrong or largely misrepresented," Del Ponte said.
Mladic is charged with genocide over the massacre in 1995 of 8,000 or more Bosnian Muslims in Srebrenica -- Europe's worst atrocity since World War II -- and for the deaths of 10,000 people during the 1992-95 siege of Sarajevo.