Developmental morphogenesis is driven by tissue stresses acting on tissue rheology. Direct measurements of forces in small tissues (0.1-1mm) in situ such as in early embryos require high spatial precision and minimal invasiveness. Here we report tissue force microscopy (TFM) integrating a vertical cantilever probe and live imaging to enable close-loop control of mechanical loading in early chicken embryos. By testing previously qualitatively characterized force-producing tissues in the elongating body axis, we show that TFM quantitatively captures stress dynamics with high sensitivity. TFM also provides the capacity of applying a stable, non-invasive and physiologically relevant load to drive tissue deformation, which alters morphogenetic progression and cell movements. Together, TFM addresses a key technological gap in tissue force measurement and manipulation in small developing embryos, and promises to contribute to the quantitative understanding of complex multi-tissue mechanics during development.