PORT ST. LUCIE, Fla. — The head of the M.L.B. players’ union said on Wednesday that the league had initially indicated that it did not intend to punish any Houston Astros players as a result of its investigation into their sign-stealing scheme, contradicting a claim by Commissioner Rob Manfred.

As players have reported to spring training this week, many have criticized the lack of punishment for members of the 2017 Astros team, which was found to have illegally stolen signs electronically on its way to a World Series title.

At a news conference in Arizona on Tuesday, Manfred tried to place some of the blame with the M.L.B. Players Association, saying that the league had originally requested to provide immunity to only a small group of Astros hitters in exchange for their cooperation with the investigation, but that the union had asked for immunity for all involved players.

“The union indicated to us that that would be a problem,” Manfred said. “We went back and suggested to them we would give them an initial list of people — players — that we would grant immunity to, preserving our ability to discipline other players. And the union came back and said that players would cooperate only if there was blanket immunity.”