"Further, the interdict also prevents workers from participating in unlawful acts such as intimidation, assault, molesting, victimisation of non-striking public service employees and members of the public."
Violence broke out on Thursday, the second day of the strike, with police using rubber bullets and water cannons against teachers and other workers in the strike in the township of Soweto.
Teachers in the red T-shirts of their union threw bricks and stones at police who fired to stop them from entering the Chris Hani Baragwanath Hospital.
The Independent Labour Caucus, one of the unions involved in wage talks with government, said it agreed with the principle with the court ruling that there must be guidance to ensure the provision of essential services.
"But in the absence of an agreement, [the injunction] can only be regarded as an interim measure. It is absolutely necessary that we reach an agreement as quickly as possible," Chris Kloppers, a spokesman for the Independent Labour Caucus, said.
Public sector unions have demanded an 8.6 per cent wage increase - more than twice the rate of inflation - and a monthly housing allowance of $137.
However, on Thursday, the government signed its last offer of just a seven per cent increase plus $96 for housing, which will cost the state $687m, which the unions have refused to accept.
The public services ministry says the deal will be implemented unilaterally if unions fail to sign on within 21 days.
On Saturday, during a speech at a public gathering, Jacob Zuma, the president, said the strike would tarnish the image of the country.
Zuma said that even during the campaigns against the apartheid government nurses were not prevented from going to work.
The last big public sector strike in South Africa took place in 2007 when a four-week strike by 600,000 state workers cost the economy several million lost working-days, discouraged investors and angered the public.