Yet the decision was immediately assailed, as public health experts, the mayors of Georgia’s largest cities and others warned that it stood to have perilous consequences. Mayors said the decision had caught them off-guard and questioned its wisdom. Business owners who were otherwise eager to revive their livelihoods said they would hold off.

The governor’s plan gives permission to gyms, hair and nail salons, bowling alleys and tattoo parlors to reopen on Friday. Then, on Monday, restaurants are allowed to resume dine-in service, and movie theaters and other entertainment venues can reopen.

“I love those people that use all of those things — the spas, the beauty parlors, barbershops, tattoo parlors,” Mr. Trump said on Wednesday. “I love them. But they can wait a little bit longer, just a little bit — not much, because safety has to predominate.”

Dr. Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases, also expressed concern. “I would tell him that he should be careful,” he said about Mr. Kemp at the White House briefing on Wednesday.