With the aim to identify small molecules able to disrupt PA-PB1 subunits interaction of influenza virus (flu) RNA-dependent RNA polymerase, and based on previous structural and computational information, in this paper we have designed and synthesized a new series of cycloheptathiophene-3-carboxamide (cHTC) derivatives. Their biological evaluation led to highlight important structural insights along with new interesting compounds, such as the 2-hydroxybenzamido derivatives 29, 31, and 32, and the 4-aminophenyl derivative 54, which inhibited viral growth in the low micromolar range (EC50 = 0.18-1.2 μM) at no toxic concentrations (CC50 > 250 μM). This study permitted to obtain among the most potent anti-flu compounds within the PA-PB1 interaction inhibitors, confirming the cHTC scaffold as particularly suitable to achieve innovative anti-flu agents.