10:00 AM PT -- Cops say they also found an "unknown liquid" in Lewis' car. They sent it to a testing lab and will file more charges if it comes back as an illegal substance.NY Giants receiver Roger Lewis was arrested for operating a vehicle while impaired over the weekend ... TMZ Sports has learned.

Lewis' 2012 Audi was initially pulled over on June 4 in Reynoldsburg, Ohio for speeding and tinted windows. But during the stop, cops tell us they smelled weed and noticed signs of intoxication.

They asked Lewis to take a breathalyzer test, but he refused.

The 23-year-old was taken into custody around 5 AM on an OVI charge. He was released to a sober friend on his own recognizance.

Lewis -- an undrafted free agent back in 2016 -- was part of Odell Beckham's infamous Miami yacht party with Trey Songz back in January. He had 2 TDs last season.

We've reached out to the Giants and Lewis' rep for comment ... so far, no word back.