(Clarifies paragraph 3 to show first air strike by warplanes) By Parisa Hafezi, Charlotte Greenfield and Gibran Naiyyar Peshimam DUBAI/ISLAMABAD (Reuters) -An Iranian strike on Pakistan this week that drew a rapid military riposte and raised fears of greater regional turmoil was driven by Iran’s efforts to reinforce its internal security rather than its ambitions for the Middle East, according to three Iranian officials, one Iranian insider and an analyst. Both the heavily-armed neighbours, oftentimes at odds over instability on their frontier, appear to want to try to contain the strains resu…