U.S. trade officials yesterday credited Reagan administration efforts with cutting steel imports, although they acknowledged that 10 months of restraints have shown that major problems remain.

The problem areas include Western Europe, where separate restraint agreements end Oct. 31, unexpected surges in imports by Canada and shipments from new suppliers trying to break into the American markets, the officials from the office of U.S. Trade Representative Clayton Yeutter told reporters.

Assistant U.S. Trade Representative Charles H. Blum said sharp decreases in steel imports in July, which were evident in figures released last week, showed that the administration's program is working.

"By and large, we are going to be able to look back and say the program did what it was supposed to do, which is to give U.S. steel makers their last chance to get their house in order so they can compete internationally," Blum said.

"So it is up to the workers and managers in the U.S. steel industry to get better and smarter," he continued.

Blum, one of the administration's leading steel negotiators, predicted that some domestic steel makers would "take advantage" of five years of import restraints, which started Oct. 1, to become internationally competitive. Others, however, will fail to improve and thus are unlikely to survive once import restraints are lifted.

Faced with a recommendation by the International Trade Commission calling for tariffs and quotas to protect domestic steel makers, President Reagan last September ordered trade officials to negotiate a series of restraint agreements with leading suppliers that would cut foreign steel sales to about 18 1/2 percent of the U.S. market.

Imports are still above that target, but restraint agreements have cut shipments from 14 countries by 29.7 percent, according to figures compiled by Yeutter's office. Industry figures showed imports captured 26 percent of the U.S. market in the first seven months of the year.

But July imports dropped to 21.9 percent of the U.S. market after being as high as 30.9 percent in January and 28.5 percent for the last quarter of 1984. July's import sag came after nine months of record foreign shipments.

Industry sources were cautiously optimistic over the results of the import restraints. "July's imports create the hope that the president's steel program may be beginning to have some effect," said Donald H. Trautlein, chairman of the American Iron and Steel Institute and head of Bethlehem Steel Corp.

But he said the drop in July imports "does little to reduce the totally unacceptable high level of steel shipped into this country this year," and called for stiffer curbs on foreign steel to bring imports down the the 18 1/2 percent level set by Reagan.

U.S. trade officials predicted imports would drop below the 18 1/2 percent level during the rest of this year as overseas suppliers make drastic cuts in their shipments to compensate for their surge in sales in early 1985.

According to the U.S. trade office figures, imports from Japan decreased by 16.4 percent, Korea by 27.2 percent and Brazil by 40.3 percent. In addition, under agreements comcluded in 1982, steel shipments from the European Community have remained steady at about 5.4 percent of the U.S. market.

But sales from Canada, which was left out of any restraint agreements after it assured the Reagan administration it "would be prudent and not take advantage of the situation," has increased its sales to record heights, trade officials said.

In addition, new suppliers have entered the market, many of them shipping illegally subsidized steel here or dumping products in the U.S. market at less that its fair value. Unfair trade cases have been filed by domestic companies against 43 of these new suppliers.

According to industry figures, imports in the first half of the year came from 76 countries, including 17 suppliers who had never shipped into the United States before. Among the leading nontraditional suppliers, trade officials said, are Austria, China, India, Norway, Peru, Portugal, Saudi Arabia, Thailand, Turkey and Yugoslavia.