"It's restrictive and every now and then it's a sharp pain so I just really want to be careful," Farmar said after the game. "I don't want to take a huge step backwards."
Farmar previously missed 10 games after suffering a tear in the hamstring on Dec. 1, but had been back in the lineup the last four games.
He is scheduled for an ultrasound on his hamstring Wednesday to evaluate the injury.
"It's extremely frustrating, but it's part of the game I guess," Farmar said.
The 27-year-old point guard came into Tuesday averaging 9.1 points and 4.6 assists on the season. He exited the Bucks game with 6:34 remaining in the third quarter, going scoreless on 0-for-5 shooting from the field in 20 minutes while collecting seven assists and four rebounds.
Farmar said he felt "a little tug" in his hamstring while playing defense in the second half, causing him to check out of the game. He said he hopes the discomfort is just being caused by scar tissue from the tear in his hamstring that recently healed.
"It's back to feeling something there now and being nervous to really just pull through it and have it tear completely again," Farmar said.
The Lakers finished Tuesday with just one healthy point guard (Kendall Marshall) in uniform. Steve Nash (nerve root irritation) and Steve Blake (right elbow) are still weeks away from returning, while Kobe Bryant (left knee) and Xavier Henry (right knee), who had both played out of position to help L.A. out at the point, are also on the mend.
Marshall finished with 10 points and seven assists in the loss.