We present the first results of extragalactic black hole X-ray binaries LMC X-1 and LMC X-3 using all the archival and legacy observations by AstroSat during the period of $2016-2020$. Broadband energy spectra ($0.5-20$ keV) of both sources obtained from the SXT and LAXPC on-board AstroSat are characterized by strong thermal disc blackbody component ($kT_{in}sim1$keV, $f_{disc}>79%$) along with a steep power-law ($Gammasim2.4-3.2$). Bolometric luminosity of LMC X-1 varies from $7-10%$ of Eddington luminosity ($L_{Edd}$) and for LMC X-3 is in the range $7-13%$ of $L_{Edd}$. We study the long-term variation of the light curve using MAXI data and find the fractional variance to be $sim25%$ for LMC X-1 and $sim53%$ for LMC X-3. We examine the temporal properties of both sources and obtain fractional rms variability of PDS in the frequency range $0.002-10$ Hz to be $sim9%-17%$ for LMC X-1, and $sim7%-11%$ for LMC X-3. The `spectro-temporal properties indicate both sources are in thermally dominated soft state. By modelling the spectra with relativistic accretion disc model, we determine the mass of LMC X-1 and LMC X-3 in the range $7.64-10.00$ $M_{odot}$ and $5.35-6.22$ $M_{odot}$ respectively. We also constrain the spin of LMC X-1 to be in the range $0.82-0.92$ and that of LMC X-3 in $0.22-0.41$ with 90% confidence. We discuss the implications of our results in the context of accretion dynamics around the black hole binaries and compare it with the previous findings of both sources.
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