Officials said the strikes were also intended as a signal to Syrian President Bashar al-Assad to keep his forces out of the region where the borders of Jordan, Syria, and Iraq meet, which was designated a de-confliction zone under an agreement between the United States and Russian Federation.
There was no immediate word on casualties in Thursday's strike northwest of the coalition base at Al Tanf, NBC News reported.
A second USA defense official said that an additional strike did hit the convoy after the vehicles continued toward the base.
Russia has condemned a U.S. coalition attack on Wednesday that it claims had hit civilians, Russian news agencies reported.
A USA airstrike has struck pro-Syrian government forces for the first time in an attack near the border with Jordan.
"The Syrian Arab Army is fighting terrorism on its territory, and no party has the right to determine the course of its operations", a source told AFP.
U.S. air strike hits pro-regime convoy in Syria
An official from a US -backed rebel group told Reuters the bombing happened after his group clashed with the militia. The Russians relayed the message to the Syrian government, but the forces did not withdraw, the official said.
It is unclear whether Russian troops were operating with the pro-Syrian government forces at the time of the attack.
Assad condemned that US strike on a Syrian airfield as "reckless", "irresponsible" and "short-sighted".
"Such actions that were carried out against the Syrian armed forces. this is completely unacceptable, this is a breach of Syrian sovereignty", Gatilov said.
Officials said the strike near Tanf hit a tank and a bulldozer and forces there, but it was not clear if they were Syrian army troops or other pro-government allies.
USA defence secretary Jim Mattis denied the destruction of the convoy, which included a number of tanks, marked an escalation in the American role in Syria.
In the end, US fighters were forced to engage the Syrian force by launching airstrikes against the convoy.
A United States official said on Thursday the attack near the town of At Tanf destroyed at least one tank and a bulldozer, while another official said they followed warning shots by U.S. aircraft meant to dissuade the fighters from advancing further.
The Special Forces are training the rebels to fight ISIS - and also accompanying them on combat missions against the militants.