Did Tiresias warn Odysseus about the Sirens?
No, Tiresias does not warn Odysseus about the Sirens, those mysterious women/ monsters whose voices could entrance the minds of men and cause sailors to wreck their ships. The goddess Circe was the one who warned Odysseus about them. Tiresias warned Odysseus about another danger.
In Book XI, Odysseus journeys to the Underworld in search of Tiresias, the famous (and blind) prophet. Tiresias foretells parts of Odysseus' journey, as well as what will await him when he returns to Ithaka. Specifically, Tiresias gives Odysseus a vague warning about the island of Thrinakia, telling him that:
[Y]ou might still come back, after much suffering, if you can contain your own desire, and contain your companions', at the island of Thrinakia, escaping the sea's blue water, and there discover pasturing cattle and fat sheep of Helios. . . and leave these unharmed[.]
The cattle of Helios were sacred, so it was forbidden to kill and eat them. Odysseus was unable to prevent his men from killing and eating the cattle once they set upon Thrinakia and began to starve, though. Thus, he incurred the wrath of Zeus.