The prop was sin-binned in the early stages of the match at the Mend-A-Hose Jungle following a challenge on Rovers full-back Lachlan Coote.
The Rugby Football League's match review panel reviewed the incident and has charged Watts with a grade B offence, resulting in a two-match ban.
Referee Chris Kendall originally issued a yellow card for a high tackle but the panel has suspended Watts for a trip in the act of tackling Coote.
Watts will therefore miss Castleford's trip to Salford Red Devils this Friday and the home game against Wigan Warriors on June 4.
Tigers head coach Lee Radford feared a ban in the immediate aftermath of Sunday's match, joking that it would have sidelined Watts for longer at the start of the season.
"I haven't watched it back but live it didn't look great," said Radford.
"I think if that was round one to six, it could have been an eight-game suspension. Now it's probably a little tick in the box."
It is Watts' second ban of the season after he was given a one-game suspension for a careless high tackle in the reverse fixture against Hull KR in February.
Wigan prop Kaide Ellis was the only other Super League player charged by the match review panel.
The Australian will miss Saturday's trip to Hull FC after receiving a one-match penalty notice for a high tackle in Wigan's defeat by Huddersfield Giants last Thursday.
Ellis sat out five games earlier in the season following a red card for punching against Catalans Dragons in Perpignan.
The Warriors will travel to the MKM Stadium one week out from the Challenge Cup final at Tottenham Hotspur Stadium, where they will face Huddersfield.
Wakefield Trinity hooker Liam Hood was cautioned for other contrary behaviour in Sunday's loss to Toulouse Olympique in the south of France.
Hood was penalised for a late hit during the game but the panel did not deem the challenge worthy of a suspension.
No foul play was found following a review of incidents involving Joe Greenwood, Oliver Wilson, Manu Ma'u, Ligi Sao, Zak Hardaker, James Donaldson, James Batchelor and George Griffin.