The pair battled it out in track during the 19-lap affair, Lawson’s first race in over a year.
The New Zealander ran 15th through the first five laps, moving by Alonso as the Spaniard ran off the road shortly after the start.
Esteban Ocon joined the pair making for an entertaining three-lap scrap at the back end of the field.
However, Alonso was left displeased with Lawson’s actions, suggesting he defended too aggressively.
“We fought very hard,” the two-time world champion said of the Sprint battle.
“He fought very hard, in my opinion, for 16th, 17th. But nothing we can do.
“As long as one of the two cars lifts off, there’s never an accident. It was my case today.
“Everyone on track is behaving as he wants,” he added.
“For me today, it was unnecessary.
“Everyone can have different opinions, I’m okay with that. It’s 24 races, so you meet somewhere in the journey.”
The key moment for Alonso happened down the back straight, where he felt Lawson almost caused a crash.
“On the straight I think we nearly crashed like I did with Lance [Stroll] two years ago at 300-something,” he explained.
“Then the way he squeezed out of the corners to the track limits itself on Lap 1 out of [Turn] 11 [the hairpin onto the back straight].
“I don’t want to make a big scene, there was of course, no penalty when someone lifts off in 16, 17, that was probably the biggest surprise.”
During the Sprint, Alonso labelled the young Kiwi an “idiot” over the radio.
The Spaniard approached Lawson following the Sprint, the pair seen having an exchange soon after climbing from their cars.
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“He said he would screw me and I guess he kept his word,” Lawson revealed.
“He was really upset, I’m not sure why.
“We were racing for P16 and I don’t know why he was so upset.
“I don’t know. It is what it is. Hopefully he can get over it and we’ll move forward.
“I understand he had a pretty horrible race so I can understand why he’s upset,” he added.
“But if I did anything wrong I’d have got a penalty.”
In qualifying for Sunday’s race, the pair headed out of the pit lane together in Qualifying 2, with Alonso passing the RB driver as they headed towards Turn 1.
“That was it,” Lawson said of the extent to the Aston Martin driver’s retribution.
“Just out of the box playing games. It is what it is, it’s part of it – it doesn’t bother me.”
Lawson is in just his sixth grand prix weekend, while Alonso will next week take the start of his 400th, the 43-year-old the most experienced driver in F1 history.
“I don’t think we have a rivalry,” he said.
“I think we just had an incident in the race and we can just get over it and move forward.”
Alonso will line up for tomorrow’s race eighth, while Lawson brings up the rear of the field following a grid penalty for additional power unit elements.
Having progressed from Qualifying 1 with ease, setting the third fastest time of the segment, Lawson then played the team game for team-mate Yuki Tsunoda, providing a slipstream down the back straight, but did not set a time of his own.
“The goal was obviously to make the most of Q1, to put everything together,” Lawson explained of his qualifying session.
“I think that’s what we did. It’s obviously positive, coming from yesterday into today, but obviously, tomorrow’s race is going to be challenging from the back.”
The United States Grand Prix begins at 06:00 AEDT tomorrow.
