The House of Representatives, by a 238-175 vote, yesterday defeated an attempt by Republicans to kill one of the most controversial sections of the omnibus trade bill and thus calm jittery world financial markets.

House Democrats, asserting that the provision sponsored by Rep. Richard A. Gephardt (D-Mo.) would not survive the conference now trying to reconcile House and Senate versions, voted on procedural grounds against the move by Republican leader Robert H. Michel (Ill.) to kill it.

The provision gained more support in yesterday's vote than it had April 29, when it squeaked through the House, 218-214. But the strong Republican showing indicated that the Democrat-controlled House would have trouble overturning a veto of the trade bill.

"I think the Gephardt amendment is bad, but I think the Michel resolution does mischief to the procedures of the House," said Rep. Sam Gibbons (D-Fla.).

The controversial amendment -- aimed at trading partners such as Japan, West Germany, South Korea and Taiwan that run large surpluses with the United States -- would require the United States to retaliate against countries that refuse to end their unfair trade practices and cut their surpluses.

The amendment has been denounced by the Reagan administration and most economists as protectionist, but Gephardt, who was campaigning in Kansas City yesterday for the Democratic presidential nomination, insisted that it is aimed at opening markets.

Michel linked the Gephardt provision to the stock market collapse last month. He warned that "the market crash has put an economic noose around the neck of the House," and "the Gephardt amendment erected the scaffolding."

Michel and other House Republicans clearly were piqued with what they saw as the partisan politics being played by the Democratic leadership. They were still angry over the move by House Speaker Jim Wright (D-Tex.) to hold open a vote on a Democratic budget late last month until he could gain a one-vote victory. Michel said he pressed his resolution yesterday without any notice because of the "untimely remarks" by Wright insisting that the House would pass a trade bill that includes the Gephardt provision this year.

The Michel resolution would have instructed the House conferees to withdraw their support for the Gephardt amendment in the negotiations with the Senate. Since the Senate did not approve anything approaching the Gephardt amendment, the Michel resolution effectively would have killed it.