In a letter on Monday to U.S. District Judge Andrew Carter in Manhattan, a lawyer for Ben & Jerry's said two weeks of mediation to settle out of court proved unsuccessful.
He asked Carter to restore Ben & Jerry's request for a preliminary injunction to block Unilever from selling the Israeli ice cream business to local licensee Avi Zinger.
Unilever has said the sale closed on June 29 and cannot be undone. A lawyer for Unilever said in a separate letter to Carter that the company is prepared for a hearing on the proposed injunction.
Reuters reported last week that the talks had broken down. A Ben & Jerry's spokesman declined to comment. Unilever did not immediately respond to requests for comment.
Ben & Jerry's had sued Unilever, which has owned the Burlington, Vermont-based company since 2000, on July 5.
It claimed that by selling the Israeli business, Unilever reneged on its promise to let the maker of Half Baked, Cherry Garcia and Chunky Monkey protect its brand.
Ben & Jerry's had in July 2021 said it would end ice cream sales in Israeli-occupied Palestinian territories because it was "inconsistent" with its values.
Israel condemned the move, and some investors sold their Unilever stocks and bonds.
Most countries consider Israeli settlements in the occupiedWest Bank illegal.
Reuters reported last week that the mediation failed because Ben & Jerry's did not want to "cave" on its social mission.
Unilever has said Ben & Jerry's had the right to make its own decisions about that mission.
The battle tests how far Unilever will give its brands freedom to have social missions.
Unilever has more than 400 brands including Dove soap, Hellmann's mayonnaise, Knorr soup and Vaseline skin lotion.
(Reporting by Jessica DiNapoli in New York and Jonathan Stempel in New York; Editing by Cynthia Osterman)
By Jessica DiNapoli and Jonathan Stempel