Alfaro re-aggravated the injury during Tuesday's game while sliding into second base.
"The biggest thing is just get rid of this inflammation so we can move forward," Miami manager Don Mattingly said.
Obtained from Philadelphia as part of the trade that sent J.T. Realmuto to the Phillies, Alfaro originally injured the knee while chasing a foul popup in the Marlins' Grapefruit League opener, banging it against a metal pole that supports the dugout railing.
Mattingly doesn't expect the issue to last more than a couple of days.
"Not concerned about opening day," Mattingly said. "Feel pretty confident about that and him getting at-bats and getting ready for that."
Alfaro hit .262 with 10 homers and 37 RBIs in 377 plate appearances for the Phillies last season. In five at-bats this spring, Alfaro has two singles.
The Marlins are expecting reserve catcher Chad Wallach back from a quadriceps injury in the coming days. A candidate to back up Alfaro, Wallach played in a simulated game Friday and should be in the lineup Sunday against Atlanta.
Wallach, son of former major leaguer and current Miami bench coach Tim Wallach, hit .161 in 56 major league at-bats for the Reds and Marlins over the past two seasons.