Validity of Restraint Clause

Hi I had accepted employment with Indian IT company and worked for Abroad client. In Abroad location Employer has established another company and contract is entered with client for providing service.My payroll was with Indian Employer and Abroad location company is not paying me anything. I have resigned from company, serve notice period and join another company in India and serve there for 4 month. After end of service with First employer and still in service with second employer, I have came across job opportunity with client of First Employer at abroad location. I have accepted that employment with Abroad client and now working with them.clean paper with second employer as well. Now, after 4 month from end of service with first employer, My first employer has served me legal notice stating restraint clause as available in Offer letter. "for one year, you shall not communicate with any customer of company not solicit to take away from company the business or any customer of company." The fact: The contract of first employer with client with which i have accepted job is still in force and also get renewed in future. Can employer claim from me any damage for loss of business. Practically there is no loss happen, payment from client to First employer are regular and contract is in force.