The Senate Judiciary Committee has postponed a July 23 subcommittee hearing where the two top U.S. antitrust regulators were scheduled to testify.

The hearing may not be rescheduled until September, according to a staff member for Mike Lee (R-Utah), who chairs the panel’s Antitrust, Competition Policy, and Consumer Rights subcommittee.

Federal Trade Commission Chairman Joe Simons (R) and Department of Justice assistant attorney general for the antitrust division Makan Delrahim gained the attention of lawmakers in recent months for their focus on big tech companies, including Alphabet Inc.'s Google, Facebook Inc., Apple Inc. and Amazon.com Inc.

The postponement comes as...