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.

The Department of Justice (DOJ) on Thursday sued to block Hewlett Packard Enterprise (HPE) from acquiring Juniper Networks, arguing that the merger between the nation’s second- and third-largest