But he said activists must now step back from their protests and focus on spreading the word in that change is possible.
Milinkevich also appealed to the European Union to press harder for the release of demonstrators arrested during the protests.
Reports said courts had begun sentencing demonstrators to 15 days in jail on charges of attending opposition rallies.
The opposition -- backed by Western government and observers -- say the poll was deeply flawed.
THE AUTHORITIES GET TOUGH: RFE/RL's Belarus Service filed these images from the police action against the March 25 demonstration in Minsk. Photographs by Maks Kapran.
THE COMPLETE PICTURE: Click on the image to view a dedicated page with news, analysis, and background information about the Belarusian presidential ballot.