The biggest pro when it comes to tariffs is that domestic goods are made more attractive because the tariff raises the prices of imported goods. The largest con, however, is that the higher prices for imported goods are passed on to domestic consumers, costing them more for those goods.
Tariffs are generally used to protect domestic manufacturers from overseas competition offering cheaper goods. The higher prices of imported goods due to tariffs often causes foreign producers to elect to withdraw from the domestic market, reducing competition. This lack of competition removes the incentive from domestic producers to find ways to lower the prices of their goods, resulting in higher overall prices for consumers, as well as a lack of innovation that competition often causes.
Tariffs also have a negative impact on the trade balance with countries against which they are used. Foreign nations often impose their own tariffs in response to domestic tariffs, raising the prices of exported gods, which causes less demand for those goods overseas. This, in turn, results in a loss of profits for domestic producers who export goods, as well as a loss of possible jobs on the domestic front because producers must lower production or withdraw from the export market altogether.