Are you allowed to go straight across the junction in the presented situation?

Why?

You cannot drive straight ahead because the officer has his back to you, signalling that you must not enter the junction. The green light shown does not allow you to proceed against the officer’s signal.

art. 5 ust. 2 Prawa o ruchu drogowym; § 108 ust. 3 rozporządzenia w sprawie znaków i sygnałów drogowych