The Wall Street Journal reported Trump had called Musk and asked him to lift restrictions on Ukraine's use of Starlink.
"I don't want to comment on it, whether I called or whether somebody else called, doesn't make any difference, I guess. The bottom line - he put it back," Trump told reporters when asked if he spoke to Musk.
Trump did not elaborate further.
Ukraine uses Starlink for battlefield communications and drone operations. Restricting the satellite service hampered the country's attack and air defence drone missions against Russia.
The Starlink system was working more normally on Thursday, shortly after the Trump-Musk conversation, the WSJ reported earlier, citing US and Ukrainian officials.
Some Ukrainian officials told the newspaper the system had not been restored to full functionality but was working at higher speeds than under the cap.
Ukrainian President Volodymyr Zelenskiy said earlier on Thursday that speed on Starlink systems had not been restored for Ukraine, adding he hoped for talks with US Secretary of State Marco Rubio in the coming days.
Trump told Musk he was frustrated the system's speeds remained capped, according to the newspaper.
Trump has denied being involved in the decision concerning the slowdown. Rubio told reporters on Wednesday that decisions regarding Ukraine's access to Starlink were up to its parent company SpaceX and Musk, not the White House.
Zelenskiy's relations with Washington have sunk to new lows after Trump announced a deal to buy Russian diesel and waived new sanctions on Moscow. Trump has also told Kyiv to stop attacking Russian refineries and urged Ukrainians to replace Zelenskiy.
Russia pounded Kyiv with ballistic missiles and Ukraine sent hundreds of drones towards Moscow on Thursday, as the warring sides kept up a barrage of attacks despite the latest US push to end the conflict. Russia launched a full-scale invasion of Ukraine in early 2022.
Trump had promised to end the war when he took office but the goal has remained elusive.
