Learning a foreign language requires students to acquire both grammatical knowledge and socio-pragmatic rules of a language. Pragmatic competence as one of the most difficult aspects of language provides several challenges to L2 learners in the process of learning a foreign language. To overcome this problem, EFL teachers should find the most effective way of teaching pragmatic knowledge to their students. Accordingly, the present study investigated the effect of explicit teaching of apology speech act, as an aspect of pragmatic competence, on the Iranian EFL learners' appropriate use of the mentioned speech act. In so doing, a total of 73 EFL students at intermediate and advanced levels participated in a pre-posttest design research with experimental and control group. Data were collected using a Discourse Completion Test (DCT). The selection of apologetic situations in DCT was based on two variables of social status and social distance. The results revealed that explicit instruction was a facilitative tool that helped students use the proper apology strategies in different situations. Moreover, it was found that L2 proficiency had a significant influence on overall appropriateness of speech act production.