Ricciardo initially got ahead of the Spaniard after a fraught battle on the first lap, and they remained close together for much of the race.
When Sainz tried to pass on lap 43 they touched, and the Ferrari driver – who suffered some front wing endplate damage – told his team “That got a bit dirty”.
Ricciardo eventually finished fifth, a place behind the other Ferrari of Charles Leclerc, while Sainz dropped to seventh behind Valtteri Bottas.
“At times it was let’s say kind of a standard progressive race or whatever, but then at times it was interesting,” said Ricciardo.
“The first lap was a lot of fun. I got Carlos I think on the start, then he got me back with a good move outside of six into seven.
“And then I got him back Turn 17 I think on the inside. So it was three kind of changes in position on the first lap was cool, but that was crucial for me to get a top five today.
“Charles showed that Ferrari were quicker, we couldn’t match that pace today. So obviously that’s something we’ve got to still try to find. But to beat one of them its quite rewarding.
“And [Sainz] put on a good attack later on in the race as well and we obviously went side-by-side, and a little bit of banging wheels. So it was very fun, and very needed to hold on for everything I could.
“Obviously you don’t deliberately try to go into someone, but that’s obviously a bit of a bit of rubbing racing.
“And when you put yourself on the outside, obviously you’re a little bit more exposed. So nothing was deliberate, but I guess it’s the risk that he ran by trying on the outside.”
Told about Sainz’s radio comment, he added: “That’s cool. I’m happy to be dirty. I’m a nice guy, so being dirty every now and then is alright!”
Ricciardo admitted that it wasn’t always easy to judge how to push on the tyres at COTA.
“It was definitely tricky, because when you come out of the pits on a new set, you have a little more grip. But if you use it early, then it drops away even quicker. It was a race where you never really felt you could push.
“I mean we’re pushing, but it’s only to what the tyre is capable of. So definitely there were some laps where you’re in a little bit of limbo, do I push more or do I not?
“And then Carlos when he started to come and attack me more, I had no choice but to push, and there wasn’t much left in it at times.”