"No information was gained, no action was taken, no follow-up whatsoever," Conway told Fox News, referring to the meeting.
Conway added that the mainstream media continues to spin its wheels in an attempt to find Russian collusion with the Trump campaign.
"What's important here is that we are at day two hundred or so of no evidence of Russian collusion," Conway said. "They [the mainstream media] want to convert wishful thinking into hard evidence."
On Saturday, US media reported that Trump Jr., along with Paul Manafort, Trump's then-campaign manager, and Jared Kushner, Trump's son-in-law, met with a Russian lawyer to discuss the suspended program of adoption of children from Russia by US citizens during 2016 election campaign.
Veselnitskaya purportedly offered to provide damaging information about rival presidential candidate Hillary Clinton as a pretext for the meeting.
In a Twitter message on Monday, Trump Jr. reiterated the meeting was about Russia’s ban on adoptions of Russian orphans by Americans and said there was "no inconsistency" in the latest reports. "In response to further q[uestions], I simply provided more details," the younger Trump stated.
Also on Monday, Kremlin spokesman Dmitry Peskov stated that Moscow was unaware of the meeting, adding that it is impossible to keep track of all Russian lawyers both inside the country and abroad.