Smoking has been recognized as a significant risk factor for COVID-19 and mortality. The World Health Organization (WHO) has recommended smoking cessation to reduce the impact of COVID-19. This study aimed to evaluate the smoking cessation rate of patients starting tuberculosis (TB) treatment at six months using motivational interviewing based on the WHO "five steps to quit" model. In addition, we assessed the knowledge about smoking and the barriers to smoking cessation. We conducted a retrospective cohort study. Outpatients aged >18 years, smokers, and those who are starting TB treatment in two outpatient TB clinics were invited to participate. Patients received information about the importance of smoking cessation, especially in TB patients, and standardized advice based on guidelines. This information was repeated during phone calls during the second and fourth months of treatment. During the study period, 111 patients were included. The primary outcome was the smoking cessation rate at the end of the sixth month of treatment, which was 26.8% (19/71). The barriers to smoking cessation described by the patients were anxiety/depression (47.4%), seeing someone smoking (38.5%), drug use (19.2%), and alcohol abuse (2.6%). The assessment of knowledge about smoking showed that patients had some information gaps. In conclusion, TB smokers who tried to quit smoking during the COVID-19 pandemic faced many challenges. Despite this, we demonstrated a reasonable smoking cessation rate with a nurse-conducted motivational interview.