Alibec played for Romania's under-17, under-19 and under-21 teams.
On 11 October 2015, after being called up on several occasions in the past, Alibec gained his first cap for the full side in the last UEFA Euro 2016 qualifying match against Faroe Islands, replacing Bogdan Stancu in the 90th minute.

In June 2016, he was picked by Anghel Iordănescu for his squad at the final tournament in France and appeared as a substitute in Romania's opening game, a 2–1 defeat to the host.
Alibec played for Romania's under-17, under-19 and under-21 teams. On 11 October 2015, after being called up on several occasions in the past, Alibec gained his first cap for the full side in the last UEFA Euro 2016 qualifying match against Faroe Islands, replacing Bogdan Stancu in the 90th minute. 
In June 2016, he was picked by Anghel Iordănescu for his squad at the final tournament in France and appeared as a substitute in Romania's opening game, a 2–1 defeat to the host.
Denis Alibec