The intention of any strike related action is to get the employer to agree to certain demands of the employees. A strike means that employees stop working and the employer is either required to shut down its business during the strike or get replacement workers in (or continue to operate with the employees who are not on strike). Strikes are usually organised by unions, which pay their members their wages in full or in part during the strike (paid for by the membership fees accumulated prior to the strike). Requirements for a lawful strike differ from country to country, but most developed countries agree that if those requirements are met, strikes are legal. A strike is therefore a state-approved form of employee blackmail.
The question therefore becomes whether the employees (aka their unions) are responsible for subsequent damages of the employer, in particular loss of profit. Case law, at least in Germany, allows such claims in the event of an unlawful strike. The situation is less for lawful strikes, though.
A recent case in Germany highlighted that problem. German air traffic controller went on strike against their employer, the German Air traffic control agency. The strike lead to disruptions of the air traffic (naturally) and after the strike was settled, several airline companies sued the air traffic union for damages. The Court held, though, that the damages were only incidental, and not a direct result of the strike. In particular it had not been the intention of the striking controllers to damage the business of the airlines. The main purpose of the strike was to get their employer, the air traffic control agency, to agree to their demands. The airlines had not been the main targets.
This sounds a bit dubious, but is probably correct from a policy point of view. After all, if striking employees could be held responsible for indirect damages it could significantly impair the right to a lawful strike.