Professional dancer Marquez is said to have been beaten up by a gang of youths in Blackpool just hours after he took part in Saturday's live show.
The Spaniard is reported to be undergoing dental surgery after having two teeth smashed.
It is believed the 26-year-old was walking to Flamingo nightclub in Queen Street, with show colleagues Aljaz Skorjanec and Neil Jones, when he was attacked.
They had recently left the Tower Ballroom, where the BBC One show was being filmed.
"We are aware that reports of this incident are in the media today," a spokesman for Lancashire Police said.
"This matter has not been reported to the police but we have made contact with the BBC this morning to try and establish details of the incident which would allow us to investigate further."
A BBC spokesman said Marquez is expected to rejoin rehearsals later in the week.
"Gorka was sadly the victim of an unprovoked incident in Blackpool on Saturday night, but he will be back in training this week and is looking forward to the group routine next weekend," the spokesman said.
Marquez's dance partner, EastEnders actress Tameka Empson, was voted out early on in the series.
He partnered singer Anastacia when Brendan Cole was unwell.
At the weekend he partnered fellow pro Janette Manrara in a routine to a Rick Astley song and he also appeared in the group dance.
The Sun quoted a friend saying it was a 'random' attack.
"Gorka and a few of the other dancers were heading to a nightclub to let their hair down after another brilliant show," the friend said.
"All of a sudden this group of local louts came out of nowhere. One of them punched Gorka in the face and broke two of his teeth."