Can Company overrule employee's resignation notice?

Today I have tendered my resignation letter with 1 month notice (as my salary is below S$2,000), but I was told by my boss that I need to fulfill the 1 year service commitment. The relevant details of my employment contract is as follows:
(i) Probation: The probation period is three months. Either party may give one week’s notice of termination during this period.
(ii) Duration: On confirmation of employment, the employment is for an agreed period of twelve months therefrom.
(iii) Notice of termination: After confirmation either party may terminate by giving one month’s notice or the payment of one month salary in lieu of notice. For an employee earning a monthly salary of S$2,000 or above 2 months’ termination notice or equivalent payment in lieu of notice from either party is required. Outstanding leave cannot be offset against the notice period without the prior consent from the firm.
(iv) Other terms and conditions: Other terms and conditions of employment not specifically provided herein should be in accordance with the firm’s practice which may be subject to such changes as the firm considers necessary to make from time to time.

Employee has the right to resign at any time by serving the required notice or by compensating the employer salary in-lieu of notice. You may highlight to your HR department that in accordance to clause (iii), you could tender by serving company’s 1 month notice. If unresolved, you may escalate your concern to MOM subsequently.