"Violence against protesters is unacceptable and cannot be allowed."
A European source said Michel decided to call the summit in view of the spike in tensions over the weekend.
Lukashenko claimed victory in the August 9 election with 80 percent of the vote, despite wide opposition to his rule.
The crackdown by security forces has seen more than 6,700 people arrested, hundreds wounded and two people killed.
EU foreign ministers on Friday agreed to draw up a list of targets in Belarus for a new round of sanctions in response to the crackdown and on Monday Germany, which currently holds the EU's rotating presidency, said it was ready to back even tougher measures.