The objects were described as suspicious packages that were examined by the Secret Service and found to be harmless. Ed Donovan, a spokesman for the Secret Service, said both were tossed shortly before 3 p.m.
The lockdown remained in force for about 90 minutes.
"An individual threw something over the north fence line and another individual threw something over the south fence line," Donovan said.
President Obama was in California for a fundraising event Thursday.
On Tuesday, an Internal Revenue Service employee was arrested when he followed a motorcade carrying the Obama daughters onto the White House grounds. Matthew Goldstein, 55, said he was unfamiliar with the area and got confused.
Goldstein was released after being charged with a misdemeanor.
"It seems to be bad luck on his part," an unnamed official told the Washington Post.