Login or register (free and only takes a few minutes) to participate in this question.
You will also have access to many other tools and opportunities designed for those who have language-related jobs (or are passionate about them). Participation is free and the site has a strict confidentiality policy.
Explanation: An infusion is defined as a "liquid produced by infusing," i.e., "by steeping or soaking without boiling in order to extract soluble elements" (American Heritage Dictionary).
If the list of ingredients of a tea product includes an "infusion" of something, I would conclude that the product is a liquid tea, like the bottled cold beverages that have become very fashionable. If this is the case, then you can despense with the phrase "infusion of" altogether. In English, the word "infusion" has a marketing value, because it evokes the exotic herbal tea-making rituals. In Arabic, a lexical equivalent will probably not have the same marketing impact. As an ingredient in a liquid, an "infusion of herbs" is equivalent to "herbs." How else can one have herbs in a drink?
If you have to have a word for it, Aisha's suggestion is appropriate.