@Efrain27 Yes, you do. As Mike and Jane said, US citizens have to report worldwide income.
But Mexico and the US have a tax treaty which prevents double taxation. So let's say you have to pay 10% tax on your rental in Mexico, but you are in a 15% tax bracket in the US- the 10% you paid is deducted from the 15%, so you'd pay 5% in the US. That's more or less how it works.
But you may also be able to deduct expenses in the US that you can't deduct in Mexico. A good accountant will know all this.