Attorney General Loretta Lynch expressed regret over a private meeting with former President Bill Clinton this week and moved to quell concerns that it could improperly influence her department’s investigation of Hillary Clinton’s use of private email to do government business.

Ms. Lynch, speaking at the annual Aspen Ideas Festival in Colorado on Friday, said she plans to accept the recommendations of career prosecutors and federal agents on whether to file charges in the email investigation, from when Mrs. Clinton, the presumptive...