The unions have set a deadline of September 2 for the government to provide a 8.6 per cent rise in salaries and a 1,000 rand ($138) monthly housing allowance, otherwise more state workers are slated to join the strikes.
The South African government is offering a seven per cent pay hike and 630 rand for housing.
Government services and the economy have already been disrupted by the strikes.
Themba Maseko, the government spokesman, said the strike had raised concern and efforts were being made to resolve it.
"We're obviously worried about the strike, especially the impact it is having on the lives of ordinary South Africans. We're actually at a point where our students are supposed to be writing their examinations in about 50 days' time," he told Al Jazeera.
"Many South Africans who are ill [and] need urgent medical treatment are being deprived of the opportunity to get that treatment. We also have a lot of South African citizens who want to volunteer their services by assisting hospitals; by assisting learners to prepare for their examininations and yet they are being prevented from doing so.
"What's worrying us the most at this particular point in time is the violence characterising the strike. There's a lot of intimidation of ordinary citizens"
Themba Maseko, government spokesman
"So what's worrying us the most at this particular point in time is the violence that's characterising the strike. There's a lot of intimidation of ordinary citizens; a lot of the workers that want to go back to work are being prevented from doing so by this violence."
Doctors and activists warned on Wednesday that HIV and Aids patients were not receiving treatment because of the nationwide strike. An estimated 5.7 million people are living with HIV and Aids in South Africa, more than any other country.
One doctor, Ashraf Coovadia, said that his HIV/Aids clinic at a Johannesburg government hospital is receiving 20 to 30 patients whereas normally the figure would be 60 to 80.
He said that clinic staff have been calling patients to urge them to come in.
Patients typically receive three-month batches of drugs. They can develop drug resistance if they miss a few days of medication.
Coovadia said that people may fear encountering violence at state hospitals or think that they have been closed by the strikes.
He added that he has had to negotiate with strikers and security guards to ensure patients can enter the clinic safely.
"The situation is quite volatile," he said.
Maine de Clercq, from the Public Workers Association, one of the striking unions, told Al Jazeera: "The government says they do not have the money and we are aware that it is above the inflation rate, but there is a policy that we will always ask for inflation plus more.
"Other government officials have already been settled and received that.
"We have eight unions in the public service [and] I represent one. We have not called for essential service workers to go on strike. We do not want people to die."
Al Jazeera's Haru Mutasa, in Johannesburg, said that strikers were on Thursday planning to march to the education and health departments with a list of their demands.
"That raises the stakes for President [Jacob] Zuma and his government. They are under more pressure now to come to some kind of an agreement with the workers and the workers have given the government one more week [to do so]," Mutasa said.
"If there is no agreement and they do not get what they want, they say that they will embark on an even bigger strike.
"They say that more people will join them and the aim then won't just be to bring the public sector to a halt but to bring the entire economy to a standstill."