The right-hander said he will appeal the decision, which was announced before the Tigers played at Toronto. He also was fined an undisclosed amount.
Porcello hit Zobrist with a high-inside pitch in the first inning Sunday. Both benches were warned, but Porcello was not ejected.
Some thought the pitch was retaliation for an inside pitch by Tampa Bay closer Fernando Rodney to Detroit slugger Miguel Cabrera the previous day. Cabrera ended up striking out, and exchanged words with Rodney on his way back to the dugout.
Detroit manager Jim Leyland said after Saturday's game that "somebody has to pay the price for that."
Leyland said Sunday that it was part of the game.
"Nobody's trying to hit anybody," he said.
But Zobrist thought otherwise.
"I thought it was intentional, and obviously the league thought that as well," he said Tuesday in Houston before the Rays played the Astros.
Zobrist was glad to see the commissioner's office punish Porcello for a pitch he thought could be dangerous.
"I was surprised, yeah. I didn't really expect anything to happen after that day," he said. "After reviewing, I assume, they must have felt some action needed to be taken."
Leyland declined comment on Porcello's suspension or the decision to appeal.
But Tampa Bay manager Joe Maddon had plenty to say about it.
"The process works," Maddon said. "Went through the proper channels and I think the appropriate retribution was doled out. We appreciate the fact that MLB looked at it and took some action. They made a decision. I think they made the right one."
Porcello, who is 4-6 with a 5.21 ERA, is available to pitch until the appeal is heard. His next start is scheduled for Friday at Cleveland.
Porcello was suspended five games in 2009 for hitting former Red Sox infielder Kevin Youkilis, which led to a bench-clearing brawl.