Praise be to Allaah.

It is not permissible to sit with people who are drinking wine (alcohol), whether they are kaafirs or Muslims. Allaah says concerning the one who sits with those who are speaking of kufr and falsehood: 

“then sit not with them, until they engage in a talk other than that”

[al-Nisaa’ 4:140 – interpretation of the meaning]

al-Tabari said: this aayah clearly indicates that it is not allowed to sit with the people of falsehood of any kind, when they are indulging in their falsehood. “(but if you stayed with them) certainly in that case you would be like them” [al-Nisaa’ 4:140 – interpretation of the meaning]. Ibn Katheer said: i.e., you would be like them in sinning. 

According to a hadeeth narrated by Jaabir, the Prophet (pecace and blessings of Allaah be upon him) said: “Whoever believes in Allaah and the Last Day, let him not sit at a table where wine is being served.” (Narrated by al-Tirmidhi, al-Adab, 2725; classed as hasan by al-Albaani in Saheeh Sunan al-Tirmidhi, 2246). The commentator on the hadeeth said: even if he does not drink with them, it is as if he is approving of their evil action. 

So it is not permissible to sit with them or to converse with them, even if one does not drink, because if he does that he is like a silent shaytaan (devil).

If you see them, then you have to denounce them for that, and if they do not respond then leave them and keep away from them. We ask Allaah to keep us safe and sound. May Allaah bless our Prophet Muhammad.