The injured included two Pakistani waiters, a Chinese, two Tanzanians and a Kenyan, said Tahir Ayub Khan, a senior police official in Islamabad, on Saturday.
"All the injured people are in a stable condition at a hospital," he said.
The explosion occurred in a bar at the club, which is run by Chinese people living in Pakistan, but is not part of the Chinese embassy, he said.
The club, along with other Chinese businesses and institutions in Pakistan, had been put on alert in May against a possible attack after a car bomb killed three Chinese workers at a port construction site in the western province of Baluchistan.
Police said the blast was an accident caused by gas leaking from an air conditioning unit.
Later, Pakistan's Interior Ministry sought to calm fears that the explosion might have been caused by a bomb.
"It was not a bomb," said ministry spokesman Abd Al-Rauf Chaudhry, adding that ministry experts had confirmed the explosion was caused by a gas leak.