Danny Welbeck scored against former club Man Utd to see Arsenal through to the FA Cup semi-finals
It was allegedly posted in the aftermath of Arsenal's FA Cup quarter-final victory at Manchester United last night, in which Welbeck scored the winner against his former club.
A spokeswoman for GMP said: “We are aware of it and are investigating.”
Meanwhile, Arsenal manager Arsene Wenger has praised his centre-forward for a battling display on a tense night at Old Trafford.
Welbeck scored when he pounced on a mistimed Antonio Valencia backpass and rounded David de Gea to tap into an empty net.
He received a warm applause from the home crowd when he was later subbed off the field and Wenger explained why he chose the 24-year-old over fellow forward Olivier Giroud.
Wenger said: “He has pace. You have as well as psychological consideration and as well I have to rotate a bit without destroying the balance of the team and I felt we had counterattacking chances and he would be ideal for that. He had a great game.”
Another player who received praise for a strong performance at Old Trafford was Alex Oxlade-Chamberlain, who set up Nacho Monreal's opener before hobbling off with a hamstring problem.
But the England international was in the mood to celebrate as he directed a mocking tweet to United left-back and compatriot Luke Shaw.
Pedro Player Profile
In transfer news, Arsenal have moved a step closer to signing £11.5million-rated Stephan El Shaarawy after the Milan midfielder expressed his gratification in being linked to the north London club.
Italian El Shaarawy, 22, is currently out injured with a broken metatarsal but that has not stopped Italian media outlets from linking him to a move to Arsenal.
He said: "I am gratified by Arsenal's interest, certainly, but my objective is to come back for Milan and do well at Milan."
Meanwhile, another Gunners transfer target, Barcelona striker Pedro, has revealed he is struggling to find form and games at the Nou Camp club.
Pedro is fourth choice behind Lionel Messi, Neymar and Luis Suarez for a starting place in Luis Enrique's side and could leave in the summer.
He is also reportedly wanted by Chelsea and Manchester United and is valued at £20m.
"I am going through a difficult period," the attacker told BeIn Sports.
"It is clear that I am having a tough time to find a place in the team at the moment. I have had few chances to play this season.
"I will consider my options in the summer and will then talk with the club to discuss my future."
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