The protesters demanded the union stand by its demands for pay hikes and the inclusion of private employees in a new contract.
A strike, threatened for next week, would involve 10,000 government social workers. Five-thousand more are employed by private firms.
Inside the building, Finance Minister Yuval Steinitz and Welfare Minister Moshe Kahlon met with Histadrut labor federation head Ofer Eini and Social Workers' Union Chairman Itzik Peri, Haaretz reported.
"There is definitely room for improvement in social workers' professional conditions, and I recognize their hard work and dedication," Steinitz said.
In the event of a strike, many services would be suspended, including probation reports and supervised child custody visits.
The social workers, who have had no raise in 17 years, want a 25 percent pay hike. The government is offering 14.5 percent.