No, it isn't, in any capacity. You seem to have no clue what the various types of monopolies or anticompetitive business practices are!
Apple has a non-coercive monopoly over macs, which reside in the larger market of personal computers. They've done all the work to create the market for them through decades of research and development, and have eaten all the risk involved in manufacturing. Apple only grants licenses to use Mac OS on Apple hardware. If you don't like that bit of the EULA, you can quite easily not accept it and not purchase or use Apple hardware or software. At which point Apple loses your business, and profit. Thus, there is competition within the sphere of personal computers, and Apple cannot dictate the terms of it. Any computer company can, without violating Apple's IP, compete with them. Quite a few do right now, in fact.
Apple doesn't license their operating system to any other manufacturers for any reason at all. Because they don't license it to manufacturers, they can't unfairly exert influence upon said nonexistent manufacturers by, say, threatening to revoke their deal with the manufacturer or increase the price of their OS licenses unless they stop carrying a competitor's product.
Not licensing their operating system is not anticompetitive. There are certainly ways that Apple could engage in anticompetitive activity, but this is not one of them. Theoretically as an example: if Apple was having a neck-and-neck battle with HP or Dell over high-end 15" laptops of a certain specification, and they informed an LCD manufacturer that they would cancel all their orders unless the LCD manufacturer stopped selling 15" panels to HP or Dell. That would probably be anticompetitive.