Even during the Brexit referendum campaign last year, the Commission kept a low profile, realizing that any perception of meddling would be punished by anti-EU media in Britain.
The top two winners on Sunday will advance to a May 7 runoff.
The attack on the Champs-Elysees came less than 72 hours before the polls open in the first round vote of the presidential election.
French prosecutors have asked the European parliament to lift the immunity of Marine Le Pen over an expenses scandal.
European authorities have pressured Facebook and Twitter to remove extremist propaganda or other postings that violate European hate speech or other laws.
France's far-right presidential contender has prompted a major outcry by denying that the French government was responsible for the roundup of Jews in World War II.
The Belgium's Olympic champion claimed his first 'Monument' title by battling through early setbacks and keeping his cool in the velodrome finale.
Skirmishes broke out ahead of a campaign rally by French far-right leader Marine Le Pen.
The sanctions, including travel bans and asset freezes, against Moscow were originally introduced in March 2014.
The Greek militant group, Conspiracy Cells of Fire, claimed responsibility for the German attack.