FIFA has a strict rule against displaying "political symbols" during matches and last year England were fined 45,000 euros (US$50,000) for wearing poppies on armbands to commemorate Armistice Day during a match against Scotland.
On Tuesday (June 13) night Qatar were playing South Korea in a vital qualifying match for next year's World Cup in Russia.
Before the game — which they won 3-2 — the Qataris players donned white T-shirts bearing portraits of the country's ruler, Emir Sheikh Tamim bin Hamad al-Thani.
Midfielder Hasan al-Haydos also waved the T-shirt to the cheering crowd after he put the Qataris 1-0 up from a free-kick in the 25th minute.
Qatar has been embroiled in a diplomatic crisis with its neighbors.
Were Saudi Arabia's footballers sending a political message after refusing to honour the London victims during a game against Australia? pic.twitter.com/WJfxdT9dFm— TRT World (@trtworld) 10 June 2017
Saudi Arabia, the United Arab Emirates, Egypt and Bahrain cut off all relations with Qatar earlier this month, claiming they are sponsoring terrorism in the Middle East.
The Saudi state news agency SPA claimed: "[Qatar] embraces multiple terrorist and sectarian groups aimed at disturbing stability in the region, including the Muslim Brotherhood, ISIS [Daesh] and al-Qaeda, and promotes the message and schemes of these groups through their media constantly."
He said wealthy individuals in both countries had been supporting extremist Islamic groups in Iraq, Syria and elsewhere but he added: "Qatar is no more a danger to the security of the region than any of the other Gulf states and it is far less dangerous than Saudi Arabia, for example."
After the game Qatar's Uruguayan coach Jorge Fossati refused to criticize his players and said: "I don't see something that can receive a punishment as it is a T-shirt with a picture of the emir."
"I can't agree with the blockade that is against the people, against the families, many families are damaged, they really don't deserve this," he added.
A FIFA official said: "We are still awaiting the official match report…we cannot comment at this stage."
Earlier this month Saudi Arabian players refused to honor a minute's silence during a match against Australia in Adelaide, which outraged Australian fans.
"After reviewing the match report and images of the match [in Adelaide], we can confirm that there are no grounds to take disciplinary action in relation to the matter," the FIFA official told Sputnik.
In the same World Cup group Iran beat Uzbekistan 2-0 to qualify for Russia.
China remain bottom of the group and now have no chance of qualifying. It will come as a major blow to China's football-loving President Xi Jinping.
Qatar will be hosting the 2022 World Cup — a controversial decision which was surrounded by allegations that FIFA officials were bribed.
Earlier this week FIFA president Gianni Infantino insisted the World Cup would go ahead in Qatar.
In an interview he said, referring to the Qatar crisis: "The essential role of FIFA, as I understand it, is to deal with football and not to interfere in geopolitics.
"Nevertheless, it is true that FIFA must remain attentive to what is happening. We are therefore watching closely the evolution of the situation."