SeaFrance had to cancel all Dover to Calais sailings after union members walked out on Friday in a row over new working practices.
It has advised customers to arrive as normal, saying they will be transferred to a crossing with another operator.
In a statement the firm said it "profusely apologised" to those affected.
SeaFrance said negotiations had been taking place to find a solution to the industrial dispute.
The ferry company normally operates 16 to 19 crossings a day between Calais and Dover. The dispute is estimated to have cost SeaFrance more than £1m.
Operation Stack - where lorries waiting to cross the Channel park on the M20 in Kent - had to be put in place throughout the day on Friday as traffic built up around the port.