Today, social media is considered as an online communication platform between companies and consumers. They make marketing activities and the buying process more effective and attractive. This study aims to study variables influencing customers' purchase intention on social media. The method of this research is a combination and integration of qualitative and quantitative methods to create a model and measure the accuracy of the model. The population of the research included the customers of food stores in Tehran, the capital of Iran. 302 people were selected as a sample and finally, all data were evaluated based on structural equation modelling. The results of this study show that the variable of persuasive messages has a positive effect on the type and value of the product, and that the type and value of the product have a positive impact on consumer behaviors and content and on how the message is designed. The variable of consumer behaviors has a positive and direct effect on the purchase intention, but the results showed that the variable of content and message design has no positive and immediate impact on the choice to buy by social media customers. The main innovation of this study is that we have measured purchase intention based on Kotler’s statement about message impacts (the three main issues), whilst other studies have not researched this aspect yet. In addition, few investigations have been done in the field of purchase intention in Iran, specially purchase intention on social media. Thus, the originality of this study is to investigate the impact of persuasive message on customers based on Kotler’s ideas about purchase intention on social media.