"In other words aluta continua, they will continue to be on strike," he told a press briefing in Johannesburg.
This would affect road freight, security, cleaners and other sectors.
It would take seven days to apply for permission for a solidarity strike.
Satawu disagreed with United Transport and Allied Unions' (Utatu) accepting 11 percent and would push for 13 percent.
Only Satawu's Limpopo branches wanted to accept.
The strike at Transnet began with Satawu on Monday, May 10. Utatu joined the next day.
Transnet employs nearly 54,000 people. Satawu represents 39 percent and Utatu 45 percent of the workers.
Satawu was still consulting its members at the Passenger Rail Agency of SA who were also on strike, and couldn't say when they would have a final decision.
Mabyana said he had been told Utatu had signed an agreement with Transnet on Friday afternoon.
Satawu believed there was no majority union at Transnet, so the Utatu agreement could not be forced on them.
They understood there was potential for violence when half the workforce returned to their posts, but union leadership and shop stewards would monitor this.
He said Satawu was still open for negotiation on the 13 percent demand.
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