he U.S. and Mexican governments today agreed to continue future discussions of trade problems although both sides said many difficulties still exist.

Both governments, after two days of meetings of the first Mexico-U.S. Joint Commission on Trade and Commerce, issued a communique' agreeing to set up further discussions between government officials to resolve separate problems that have disturbed relations between both countries.

While the U.S. delegation, headed by Commerce Secretary Malcolm Baldrige and U.S. Trade Representative William Brock, stressed the need for open trade between the countries, the Mexicans, led by Mexican Commerce Secretary Jorge de la Vega, said it is necessary for them to increase exports to the United States to meet their import requirements.

The meeting was intended to devise a framework for future discussions between the two countries in which trade has flourished during the last decade, but systems for handling that trade have not kept pace. The Mexicans recently instituted protectionist policies to improve their $2.4 billion trade imbalance with the United States, to help industries increase exports and to reduce unemployment. The Mexicans have imposed tariffs, quotas and subsidies to help build their fledgling industries. The Mexicans contend those incentives are necessary to help improve their economy. Both sides agreed to further discuss the issue.

Brock said in an interview today that the discussions helped to "reduce the magnitude of the problem. We simply do not have enough knowledge of Mexican law. . . . It was an opportunity to learn a lot more about what each is doing."

The Mexicans have been concerned about the United States selling its strategic reserves of silver, which they contend would depress the price of silver, one of their important commodities. The U.S. delegation invited the Mexican govenment to continue discussions with U.S. officials on that issue. Another problem point for the Mexicans is that several members of Congress have proposed graduating Mexico from a program providing tariff benefits for developing nations. Those congressmen have said some Mexican businesses are competing too successfully with U.S. firms and no longer should receive special benefits. The U.S. officials said in the communique' that they will continue to provide the benefits for Mexico but monitor the situation annually.

The United States also offered to consult with the Mexicans on a product-by-product basis where appropriate as far as preferential tariff treatment is concerned. The Mexicans, however, said they continue to oppose their graduation from the program, the communique' said.

One area that has disturbed U.S. businessmen has been the restrictions on auto-parts production and imports into Mexico in an effort by the Mexican government to bolster its auto industry. Both delegations agreed to set up a group to further study the auto problem, as well as trade in petrochemicals, computers and textiles.

U.S. government officials have been concerned that further protection by the Mexicans of their auto industry could lead to an influx of cheap automobiles in U.S. markets in the next decade, similar to the problem Detroit auto manufacturers had with Japanese imports.

Both sides said the talks were more pleasant than those held in the past under the Carter administration, in which relations were frequently tense. President Reagan and Mexican President Jose' Lo'pez Portillo set up the joint commission during a meeting in Camp David last June. Brock and Baldrige met with Lopez Portillo today and Brock said the talks were friendly.

Brock said in an interview that although no concrete trade agreement resulted from the discussions, progress was made because the two countries, which have suffered political and trade tensions in the past, are beginning to openly discuss their problems.