Local elections have been held in the occupied West Bank and in one Gazan city, though Hamas and other groups are not taking part.
The 300 couples were selected in a draw of nearly 2,000 people to be a part of the joint celebration.
Witnesses report clashes in the centre and north, in what has been described as the largest jihadist attack in years.
The city of Dnipro was hardest hit, with officials saying four died in a strike on a residential building.