Riggleman reiterated that the team did not talk to him about taking over the club on an interim basis.
"That report came out on Saturday right before we were playing our game in Tampa," said Riggleman by phone. "That was the first I heard of it.
"It was kind of embarrassing for all of us. My understanding is that it was an unfounded report.
"We are going on as is. We are going to try to win ball games. Manny is doing everything he can to right this ship. [Acting general manager] Mike Rizzo is doing everything he can do. All of the coaches are supportive of Manny. We are totally supportive of Manny. We plan on going to work tomorrow and get this thing going."
Entering Tuesday's action, the Nationals are 16-45, the worst record in baseball.
According to one of the team sources, the Nationals have considered letting Acta go since late May but decided first to relieve Randy St. Claire of his duties as pitching coach on June 2. Washington hired Steve McCatty to replace St. Claire.
At the time, Rizzo said the team needed more of an old-school pitching coach, and it is unclear whether that maneuver would be given more time to possibly stabilize Acta's standing.
SI.com also reported that the Nationals would consider hiring Bobby Valentine as manager of the team. Rizzo declined to comment on the report.
Valentine, who is currently the skipper of the Chiba Lotte Marines in Japan, has not managed in the United States since 2002. He is a combined 1,117-1,072 with the Rangers and the Mets. His best year was in 2000, when he guided the Mets to the World Series.
Bill Ladson is a reporter for MLB.com.
This story was not subject to the approval of Major League Baseball or its clubs.