Texas Rangers catcher Geovany Soto is apologizing to teammates, fans and his bosses ... saying he's "embarrassed" after being arrested for weed possession last night. 

The 31-year-old former NL Rookie of the Year was pulled over for speeding in Grapevine, TX around 10PM Wednesday night ... and during the stop, cops say they found a small amount of pot. 

Soto was ultimately arrested for marijuana possession -- and was hauled to a nearby station where he was booked and posed for a mug shot.  He was released on $500 bail. 

Moments ago, Soto issued a statement saying, "I was stopped by Grapevine Police on Wednesday night. I am embarrassed and would like to apologize to my family, the Rangers organization, and our fans that I was taken in on this charge."

He added, "Because this is an ongoing case, I cannot discuss this matter any further at this time.”