Police have been called to deal with issues arising between customers and CalMac staff at the ports of Mallaig and Ardrossan, both ferry terminals which have lost considerable numbers of daily services with almost no warning in order to meet the shortfalls in services elsewhere caused by the withdrawal of MV Hebrides from service.
Robbie Drummond, the managing director of CalMac, said on Twitter: "I know frustrations are running high but please treat our staff with respect - they are doing their utmost to help customers.
"Police have been asked to attend Mallaig and Ardrossan.
"Aggressive behaviour towards our staff is unacceptable and will not be tolerated."
One Twitter user commented: "Sad that the frontline staff who in reality go out of their way to help customers are the people who ultimately bear the frustration of travellers for the failings of their superiors.
"The port staff are nothing short of brilliant. It's time their superiors got their act together."