WASHINGTON — President Volodymyr Zelensky of Ukraine spoke with more than 300 members of Congress on Saturday, imploring them to ban the importation of Russian oil and to send more jets to his country, according to lawmakers on the call.The meeting, conducted via Zoom, was the first time Mr. Zelensky had addressed both houses of Congress since Russia’s invasion of Ukraine.During the call, Mr. Zelensky waxed defiant, according to lawmakers on the call. He told the lawmakers it might be the last time they see him alive, echoing comments he made last month on a call with European Union leaders.Mr. Zelensky reiterated a list of his long-sought after demands, including the imposition of a no-fly zone over Ukraine. Western governments have rebuffed the idea as all but impossible, citing the risk of direct conflict between NATO and Russian forces.“He is standing strong, but pleaded for more help,” Representative Jim Himes, Democrat of Connecticut, said of Mr. Zelensky. “Planes, oil embargo, continued military aid.”Mr. Zelensky told lawmakers that a ban on Russian oil would be “even more powerful” than removing some Russian banks from the SWIFT financial messaging system, according to Senator Dan Sullivan, Republican of Alaska. This past week, Republicans and Democrats ratcheted up pressure on the White House to prohibit the importation of Russian energy products, even though experts have said such a move would be largely symbolic.Lawmakers have also been urging the administration to ship more military equipment to arm the Ukrainians, even after Mr. Biden last weekend authorized the shipment of a $350 million package of weapons to the country, a package that represented the largest single authorized transfer of arms from U.S. military warehouses to another country.On Saturday, Mr. Zelensky stressed the need for additional planes and drones in the absence of a NATO-led no-fly zone, lawmakers on the call said. His plea came after Poland, Bulgaria and Slovakia said they would not send fighter jets to Ukraine.“Zelensky’s message is simple: ‘Close the skies or give us planes,’” Senator Ben Sasse, Republican of Nebraska, said in a statement after the meeting. “Let’s be cleareyed about our options: A no-fly zone means sending American pilots into combat against Russian jets and air defenses — in a battle between nuclear powers that could spiral out of control quickly.”Mr. Sasse added that the United States “should absolutely send Ukrainians planes, helicopters and U.A.V.s,” or unmanned aerial vehicles.In an interview after the call, Representative Tom Malinowski, Democrat of New Jersey, suggested that Congress quickly approve funding to reimburse Eastern European allies if they provide Ukraine with planes — or more feasibly, he said, surface-to-air missiles.“We should be signaling to the Poles and Romanians and others that this is something we would want to help them do,” Mr. Malinowski said.Senator Chuck Schumer, Democrat of New York and the majority leader, pledged to Mr. Zelensky during the call that he and Senator Mitch McConnell, Republican of Kentucky and the minority leader, were working “very hard in a bipartisan fashion” to quickly approve the $10 billion aid package to Ukraine that the Biden administration requested this past week.“President Zelensky made a desperate plea for Eastern European countries to provide Russian-made planes to Ukraine,” Mr. Schumer said in a statement. “These planes are very much needed. And I will do all I can to help the administration to facilitate their transfer.”On the call, Mr. Zelensky also asked for Western governments to impose additional sanctions on Russia. And in a tart aside, he said he believed that Russia would not have invaded Ukraine if the penalties recently imposed by the Biden administration and European governments had been enacted in the fall, according to two people familiar with the comments.