Canadian Ambassador Allan E. Gotlieb yesterday urged American congressmen to stand firm against protectionist pressures from their constituents, declaring that laws restricting imports will hurt the United States as well as its trading partners in the world.

"Seeking a quick fix for politically expedient reasons today is to guarantee a much more ominous future," the Canadian ambassador told the Woman's National Democratic Club.

Gotlieb's speech showed the depth of concern in Canada--the United States' largest trading partner--over protectionist measures expected to come before Congress this year. The ambassador was reported to have picked the Woman's National Democratic Club as his forum in an attempt to blunt the protectionist strains appearing in the preliminary platforms of candidates for the 1984 Democratic presidential nomination, particularly front-runner Walter F. Mondale.

Gotlieb said that American congressmen and senators, with their independence from party discipline and ability to introduce legislation without administration approval, appear especially vulnerable to protectionist "demands from local and special interest groups." Some congressmen sponsor trade restrictions as "special cases" while decrying protectionism as a philosophy, he added.

He described as "worrisome" the trend of the new Congress--called by House Speaker Thomas P. O'Neill the most protectionist in the past 32 years. It appears that a growing number of bills to protect American industries will be dropped in the hopper.

"There is much talk of legislating trade reciprocity to force other countries to trade fairly. But fair trade, like beauty, is in the eyes of the beholder. The unilateralism and selectivity of the proposed reciprocity legislation could well make things much worse, for the U.S. as well as other countries," said Gotlieb.

He said congressional debates make it appear that only the United States plays fair in trade "while the rest of the world is illegitimately restrictive." But, quoting a study by Dr. William Cline of the Institute for International Economics, Gotlieb said the United States uses nontariff barriers to protect its industries far more than most people think--and, in fact, more than Canada does.