WASHINGTON—The U.S. and China are about to declare a pause in their trade war by signing an initial pact this week, but a continuing battle over technology is bound to keep relations between the two superpowers on edge.

The Trump administration’s immediate focus is tightening restrictions on Huawei Technologies Co., the giant Chinese telecommunications company that the White House and Congress view as a national-security threat. The Commerce Department recently sent regulations to the Office of Management and Budget that would...