The club has had two players sent off in its first four Premier League games.
Aleksandar Mitrovic was dismissed for a clumsy challenge on Arsenal’s Francis Coquelin in last weekend’s 1-0 home defeat.
The striker’s early dismissal left Newcastle to play 75 minutes with 10 men.
Defender Daryl Janmaat was also sent off for a second bookable offence in Newcastle’s 2-0 away loss to Swansea City last month.
“When you play 10 against 11 it’s hard, and when you play against a big team like Arsenal it’s too hard,” said Sissoko, preparing for tomorrow night’s friendly against Portugal in Lisbon.
“We tried to do our best. We showed some good things.
“Defensively, we were very good, and they scored in the second half.
“We have to learn about this game and try to be careful with tackles and fouls. We have to try to stay 11 (men on the pitch) and win the game.”