Organic revenue fell in every region, including by 9% in Asia Pacific, although performance was ahead of ad spend forecasts.
WPP said "inappropriate and offensive behaviour is not tolerated."
Stock price underwent a temporary bounce as investors considered the move a vote of confidence.
Race hots up for US pharmacy giant's integrated account.
Drinks giant reached decision despite coronavirus outbreak.
Havas has run the airline's business for six years.
Top news, insights and analysis every weekday
Sign up for Campaign Bulletins