The incident was said to have happened as Mr Galloway gave a talk in the university's New King's building.
He tweeted that he had an "unknown substance in my eyes and lungs" but added later that he was "feeling better... just needed a good shower".
Police confirmed they had been called to a disturbance at 19:45.
Mr Galloway, who is from Dundee, also tweeted: "Someone calling themselves "Trans" and an "anarchist" led a five person attack on me on the platform at Aberdeen University. I continued."
He also said on Twitter that his pregnant wife had leapt forward to defend him.
A Police Scotland spokesman said officers had attended High Street in Old Aberdeen following reports of a disturbance.
"Inquiries are at an early stage and no further details are available at this  time," he said.

Tens of thousands of pilgrims joined him for the Way of the Cross ceremony, recalling Jesus' crucifixion.
Among the cross bearers were Syrian and Iraqi refugees, and Nigerians who had escaped Boko Haram persecution.
The service came a day after almost 150 people were killed in an al-Shabab attack on a Kenyan university.
"We still see today our persecuted brothers, decapitated and crucified for their faith in you [Jesus], before our eyes and often with our complicit silence," Pope Francis said, presiding over the ceremony at the Colosseum.
Earlier, he condemned the attack in Kenya, where Christians were singled out and shot, as an act of "senseless brutality".
In another Good Friday ceremony, Pope Francis listened as the Vatican's official preacher Raniero Cantalamessa denounced the "disturbing indifference of world institutions in the face of all this killing of Christians".
He too mentioned the Kenya attack, as well as the beheading of 22 Egyptian Coptic Christians by Islamic State (IS) militants in Libya in February.
Pope Francis has spoken out against the persecution of Christians before, saying that the world would be justified using military force to combat the "unjust aggression" by IS.

Max Jowitt crossed early on after good work by Craig Hall, but three quick tries by Tony Gigot, Dave Taylor and Justin Horo put the hosts in control.
Wakefield drew level at 18-18 at the break when Jonny Molloy powered over and Hall touched down.
The teams both scored two further tries but Pat Richards missed a late kick with his side trailing by two at 30-28.
And Wakefield, who were already assured of their place in the top eight, held on for a victory which ends a three-match losing run.
The Wildcats had regained the lead after an even first period when Bill Tupou made the most of some quick thinking by Hall to go over.
Catalans responded again when Morgan Escare ran onto a Lucas Albert kick.
Mikey Sio then crossed for the visitors and the reliable boot of Liam Finn made it 30-24, but although Fouad Yayha scored in the corner, Richards' missed conversion proved costly for Catalans.
Catalans Dragons: Escare, Yaha, Garcia, Duport, Richards, Gigot, Albert, Baitieri, Taylor, Horo, Maria, Pelissier, Casty.
Substitutes: Bousquet, Da Costa, Mason, Navarrete.
Wakefield: Jowitt, Lyne, Arundel, B Tupou, Hall, Miller, Finn, Simon, Moore, Arona, Ashurst, Molloy, Sio.
Substitutes: Scruton, A Tupou, Walton, Fifita.
Att: 8,562.
Ref: Chris Campbell (RFL).
Police were called to the University of Aberdeen following reports that a group of protesters had thrown glitter over former MP George Galloway.
[NEXT_CONCEPT]
Pope Francis has condemned the "complicit silence" about the killing of Christians during a Good Friday service in Rome.
[NEXT_CONCEPT]
Wakefield moved up to sixth in Super League after edging a thrilling topsy-turvy encounter with Catalans Dragons.