WASHINGTON—The Justice Department on Thursday sued to block the tie-up of Hewlett Packard Enterprise and Juniper Networks, a $14 billion deal that would join the second-largest and third-largest providers of wireless networking solutions for large corporate customers.

U.S. government regulators sued to block Hewlett Packard Enterprise’s $14 billion acquisition of rival Juniper Networks on Thursday, saying the combination would eliminate competition, raise prices and reduce innovation.

Hewlett Packard Enterprise shares are trading lower Thursday after the U.S. Department of Justice (DOJ) filed an antitrust lawsuit to block its proposed $14 billion acquisition of Juniper Networks.