Morocco had agreed to play Argentina's strongest team this week, so the FRMF was disappointed to learn of Lionel Messi's injury.
The Royal Moroccan Football Federation (FRMF) sought clarity regarding Lionel Messi's injury, having been frustrated to learn that Argentina would be without their star man for Tuesday's friendly.
Messi released from squad after Argentina return in Venezuela defeat
Messi made his return to the international stage last week, but Argentina were beaten 3-1 by Venezuela in Madrid and the Barcelona star was later revealed to be suffering with a pelvic injury.
That ailment will keep Messi out of Argentina's trip to Tangier, as was confirmed to Morocco in a letter on Saturday.
But having agreed with Argentina that their best team would be on show, the FRMF asked for a further explanation, seemingly seeking to ensure Messi's injury is genuine.
Agreement was to play "Argentina's first team", Morocco complain
A statement from the federation read: "The FRMF on Saturday received a letter from the agent of the friendly match against Argentina, officially confirming the absence of Lionel Messi.
"According to the same letter, the agent confirmed that the Argentine Football Association said that Messi had been injured in a match against Venezuela on Friday in Madrid, and that he directly joined Barcelona for treatment.
"The FRMF asked for clarification from the match agent, approved by the Argentine Football Federation, after news of Messi's absence from Tuesday's match in Tangier.
"It is worth noting that the FMRF had agreed in the contract organising this friendly match to face Argentina's first team."
Morocco were held to a 0-0 draw by Malawi in an African Nations Cup qualifier on Friday.