Bring a large pot of lightly salted water to a boil. Cook elbow macaroni in the boiling water, stirring occasionally until cooked through but firm to the bite, 8 minutes; drain. Rinse macaroni with cold water until cool; drain.
Mix macaroni, chicken, mayonnaise, pineapple with about half the reserved juice, cilantro, red onion, and salt together in a large bowl.
Cover bowl with plastic wrap and refrigerate until chilled, at least 15 minutes.