For at least a week, the Ukrainian leader said his country had not received early warnings about ballistic missiles aimed at the capital.
Such intelligence, he said, saves lives by allowing the public to be alerted and giving military units time to try to intercept the missiles.
Elon Musk last week ordered the slowdown of a military-grade version of Starlink that Ukraine relies on, the Wall Street Journal reported on Tuesday.
Zelenskiy said the change happened after talks with his American counterparts, including a phone call with Secretary of State Marco Rubio.
"We are thankful that intelligence works now, and I'm speaking about early warning, which is very important for our people, for children, adults, civilians, because we can hear when ballistic is coming," Zelenskiy said during a visit to Norway.
"So we are thankful to American side now that it works."
Zelenskiy said he had "a substantive conversation" with Rubio.
"I am grateful for his readiness to help and his clear position," Zelenskiy said on X.
Speaking to reporters in India, Rubio acknowledged mutual frustration between the US and Ukraine over intelligence sharing and weapons supplies but emphatically denied that the Trump administration had made any changes to previous policy on either issue.
In other developments, Russia unleashed another missile and drone blitz of civilian areas in Ukraine, killing at least nine people, officials said.
Zelenskiy was joined in Norway by US envoy Steve Witkoff and Norwegian Prime Minister Jonas Gahr Støre and Finnish President Alexander Stubb.
Witkoff then headed to Russia to meet with Russian leaders, exchange ideas from the Oslo meeting and share proposals from European and American colleagues.
"Today was a good day for peace," Stubb said.
In a post on X after the talks, Zelenskiy wrote: "Ukraine immediately supported American proposal for an energy ceasefire. But Russia responded by continuing its attacks".
"Thank you to everyone who stands with Ukraine and stands for peace."
He said his government has "some clear ideas" on how to reach peace and wants the US negotiators to "take these ideas to the Russians".
The Oslo meeting was part of a renewed diplomatic push by Trump, whose recent efforts have focused on reaching an understanding with Moscow, while stepping up pressure on Ukraine.
Speaking in Washington on Monday, Trump again criticised Zelenskiy, saying the Ukrainian leader was "not really helping" efforts to end the war.
"We want Zelenskiy to make a deal," Trump told reporters.
"We've given a lot to Ukraine. We've gotten absolutely nothing back except grief, death, tremendous monetary loss."
If that doesn't happen, "I think it's going to be a very bad thing."
Trump also recently called Kiev's long-range strikes on Russian oil infrastructure a "disgrace" and blamed them for high US energy prices - an issue weighing on his Republican Party's prospects ahead of next month's congressional elections.
Russian Foreign Minister Sergey Lavrov said Moscow was willing to listen to new US proposals about Ukraine but doesn't expect any "miracle" from Washington.
Ukraine has nearly run out of American-made Patriot air-defence interceptors that it needs to stop Russian ballistic missiles, according to Zelenskiy, who has pleaded for Washington to send more.
But he said the Pentagon was delaying the delivery of missiles that other countries had purchased for Ukraine.
with Reuters and dpa
