European Energy Security and Diversification Act of 2019 This bill directs the Department of State to prioritize assistance to develop energy infrastructure in Europe, in particular for projects involving the European Commission and governments in the region. Assistance shall include political, technical, and diplomatic support. Projects eligible for such assistance include infrastructure for natural gas, electricity transmission, and renewable energy. The State Department shall give preference to projects that (1) improve the capacity to transfer gas and electricity within and between European countries, (2) have been identified by the European Commission as integral for regional energy security, (3) are expected to enhance energy market integration, (4) can attract other sources of funding, and (5) can potentially use U.S. goods and services. The bill reauthorizes through FY2021 the Countering Russian Influence Fund and establishes that U.S. agencies may use the fund to provide assistance under the bill. The President shall report to Congress annually about U.S. assistance provided under the bill.