SANTA CLARA, Calif. -- A minor foot injury is preventing San Francisco 49ers linebacker Aldon Smith from fully participating in the team’s three-day mandatory minicamp, though first-year head coach Jim Tomsula hardly seems concerned.

Smith, who missed nine games in 2014 while serving an NFL suspension, was hurt during the 49ers’ organized team activities (OTAs) prior to the start of the minicamp when he was stepped on by a teammate.

That has relegated Smith -- San Francisco’s top pass-rusher -- to a bystander role during full team drills this week after he aggravated the injury again on Tuesday.

“We’re not going to push it,” Tomsula said. “He’s got the ice bags on and there’s really nothing else to do. If it was something in the season, we’d play right through.”

Smith is a huge part of the 49ers’ suddenly depleted defense, so it makes sense that the team wants to take a cautious approach. The seventh overall pick in 2011, Smith has 44 sacks in 50 games during his four-year career.

San Francisco can ill afford to lose the 6-foot-4, 265-pound pass-rusher. Defensive end Justin Smith and linebackers Patrick Willis and Chris Borland all retired in the offseason, and the 49ers have been scrambling to replace them since.

Here are some other news and notes from Wednesday’s practice:

• Veteran defensive lineman Glenn Dorsey has been getting work in at left defensive end during the minicamp. Dorsey’s main position is at nose tackle and he is still taking reps in the interior of the line, but the 49ers want to take advantage of Dorsey’s versatility and plan to use him on a part-time basis at defensive end.

• First-round pick Arik Armstead is one of the few no-shows but he has a legitimate excuse. NFL rules prohibit rookies from joining their teams until their college class has graduated, unless the player has graduated early. Armstead dropped out of college late in the year to prepare for the NFL draft but can’t rejoin the 49ers until Friday -- one day after the minicamp ends.

• Daniel Kilgore started seven games at center in 2014 before a broken leg prematurely ended his season. Kilgore has been slow to mend and the team is holding him out of all offseason practices as a precaution. The hope is that Kilgore will recover in time for the start of training camp next month. In the meantime, Joe Looney and Dillon Farrell have been sharing the center duties.

• Safety Eric Reid took to Twitter to refute a story saying he had contemplated retiring in the offseason after suffering three concussions in two years. Reid said his words were taken out of context and that he evaluates his situation after every season, regardless of his health.

• Quarterback Colin Kaepernick threw a crisp 40-yard completion to tight end Vernon Davis during a passing drill. Later during a team scrimmage, Kaepernick tried to force a pass in the end zone into double coverage and was intercepted by rookie safety Jaquiski Tartt.