David Boon of the Emirates Elite Panel of ICC Match Referees imposed the suspension after Sri Lanka was ruled to be three overs short of their target at the end of the match when time allowances were taken into consideration.
Mathews pleaded guilty to the offence and accepted the proposed sanction so there was no need for a formal hearing.
In accordance with Article 2.5.2 and Appendix 2 of the ICC Code of Conduct, which deals with serious over-rate offences, the captain receives two suspension points while the players are fined 10-per-cent of their match fees for each of the first two overs short and 20-per-cent for every additional over their side fails to bowl in the allotted time.
Two suspension points in the Code equates to a suspension from one Test or two ODIs, to be applied to the subsequent International Matches in which the player sanctioned is most likely to participate in.
As such, Mathews has been suspended for the first two ODI against South Africa to be played on 20 and 23 July at R.Premadasa Stadium in Colombo, while his players have been fined 40-per-cent of their match fees.
The charge was laid by on-field umpires Nigel Llong and Peter Nero, third umpire Joel Wilson and fourth umpire Nigel Duguid.