Apple sued Motorola Mobility on Friday in an effort to stop Motorola from asserting some patent claims against Apple in Germany, according to the lawsuit. The suit was filed in a San Diego federal court (Apple Inc. and Apple Sales International v. Motorola Mobility Inc., 12-cv-355.) It argues that Motorola's German lawsuit against Apple breaches terms of a patent licensing agreement between Motorola and Qualcomm.

According to sources, European regulators are expected to clear Google's planned $12.5 billion purchase of Motorola Mobility soon. U.S. antitrust authorities are also expected to give a green light to the deal.

Earlier this week, Google pledged to license Motorola patents on fair and reasonable terms if the deal succeeds.

Apple accused Motorola of pursuing an aggressive campaign of litigation that "flies in the face" of its promise to license standards essential patents on fair and reasonable terms.

Apple says is a third-party beneficiary of Motorola's agreement with Qualcomm. Under that agreement, Motorola's rights under certain patents are exhausted, Apple argues.