Igarashi, who had an MRI at the Hospital for Special Surgery on Wednesday, "will progress to baseball activities as tolerated," the club said in a news release.
In order to fill his spot on the 25-man roster, the Mets recalled right-hander Manny Acosta from Triple-A Buffalo. Acosta will be available for Wednesday night's game against the Cubs at Citi Field.
Igarash, a veteran of Japanese professional baseball, had a 1.35 ERA through 6 2/3 innings in his first year in the Major Leagues. The 30-year-old right-hander strained his left hamstring in the eighth inning of the Mets' 4-0 win over Chicago when he squatted to field a bunt. Igarashi then faced two additional batters, but he was removed after a visit to the mound by the trainer.
The 28-year-old Acosta, who was claimed off waivers from the Braves in late March, appeared in five games for the Bisons in 2010, posting a 2.16 ERA in 8 1/3 innings.
Alden Gonzalez is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.