The European digital marketing company has briefed Pleon to target media-buying agencies and marketing personnel.
Media relations will focus specifically on trade titles, such as Haymarket's Campaign and Revolution.
Senior account manager Joanna Lane is overseeing the account.
Despite opening a UK sales office last year, InteractiveMedia has been disappointed with its performance. The company is headquartered in Germany, where it currently works with Pleon Dusseldorf.
InteractiveMedia is part of the Deutsche Telekom Group, and offers services from online advertising, e-commerce and market research to affiliate marketing.
It has run a number of pan-European campaigns for companies including Panasonic and Nike.