C.L.
If its a matter of him not being able to communicate with you, then give him a way. Especially if its something he can have anyway, like one of his toys.
When my daughter was that age, we used the phrase "Show me." She would take our hand and lead us to what she wanted. It gave her a sense of control of the situation and let her tell us what she wanted.
If he's having a tantrum to get something you don't want him to have, then this is where it gets painful as a parent. Tell him firmly, "No" and then leave it at that. Let him scream and cry, and be consistent. The more you give in, the more he learns that volume and tears will get him what he wants.
As he gets older you can start pairing this up with timeouts or even taking away toys/treats/privilges or whatever you find works best.